Joint warfare in South Vietnam 1964-1968

Template:TOC-right In the Vietnam War, after the Gulf of Tonkin incident in 1964 and the continuing political instability in the South, the United States made a policy commitment to begin joint warfare in South Vietnam, involving the commitment of large-scale combat forces from the United States and allied countries. It was no longer assumed the Republic of Vietnam could create a desirable situation without major external assistance. This phase of the war lasted until the election of Richard M. Nixon, and the change of U.S. policy to Vietnamization, or giving the main combat role back to the South Vietnamese military.

Robert McNamara suggests that the overthrow of Duong Van Minh by Nguyen Khanh, in January 1964, reflected different U.S. and Vietnamese priorities.

"And since we still did not recognize the North Vietnamese and Vietcong and North Vietnamese as nationalist in nature, we never realized that encouraging public identification between Khanh and America may have only reinforced in the minds of many Vietnamese that his government drew its support not from the people, but from the United States."

Minh's government had been exploring neutralist solutions, which did not fit within the broad anti-communist containment policy of the United States.

Roughly until mid-1965, the SVN-US strategy still focused around pacification, both the earlier Strategic Hamlet Program and its successors, but it was increasingly irrelevant in the face of larger and larger VC conventional attacks. In 1965, the Johnson Administration chose a strategy focused on the defeat of the enemy force in the field, rather than on population security.

Politically, 1966 had its Buddhist crisis, but, at the end of the year, some steps toward constitutional government in the South.

There were, however, changes in the overall situation from early 1964 to the winter of 1965-1966, from 1966 to late 1967, and from late 1968 until the U.S. policy changes with the Nixon Administration.

The strategic situation

Military developments in this period should be considered in several broad phases that do not fit neatly into a single year:

• Gradual intensification, and North Vietnamese exploration of a changed ground environment. Significant events include the Battle of the Ia Drang and the Battle of Bong Son, as well as joint "search and destroy" operations against Communists. During this period, the U.S. concept of the joint war developed.
• A North Vietnamese strategic buildup for what they saw as decisive actions in 1967-1968
• The 1967-1968 campaign, which appears to have had a broader concept, not executed, than the most obvious aspects of the Battle of Khe Sanh and the Tet Offensive.

The U.S. plans

Some fundamental decisions about U.S. strategy, which would last for the next several years, took place in 1965. Essentially, there were three alternatives:

1. Bombing, enclave and rural security, principally supported by U.S. Ambassador to South Vietnam, Maxwell Taylor GEN (U.S. Army, retired)
2. Attrition of VC bases and secondarily personnel, the focus of GEN William Westmoreland, commanding general, Military Assistance Command, Vietnam. Westmoreland, in a March 26 message, said that it would take six months for air attacks to take effect, and third-country ground troops were needed immediately. Westmoreland stated "search and destroy" as a goal in May
3. Emphasis on rural security, from a number of U.S. Marine Corps officer including then-LTG Leonard Cushman, then-MG Victor Krulak, and others

Even with these three approaches, there was still significant doubt, in the U.S. government, that the war could be ended with a military solution that would place South Vietnam in a strongly anticommunist position. In July, two senior U.S. Department of State officials formally recommended withdrawal to President Lyndon B. Johnson; Secretary of Defense Robert McNamara, at the same time, saw the situation as bad but potentially retrievable with major escalation.

Westmoreland's "ultimate aim", was:

"To pacify the Republic of [South] Vietnam by destroying the VC—his forces, organization, terrorists, agents, and propagandists—while at the same time reestablishing the government apparatus, strengthening GVN military forces, rebuilding the administrative machinery, and re-instituting the services of the Government. During this process security must be provided to all of the people on a progressive basis." Source: Directive 525-4 (MACJ3) 17 September 1965: Tactics and Techniques for Employment of US Forces in the Republic of Vietnam

Westmoreland complained that, "we are not engaging the VC with sufficient frequency or effectiveness to win the war in Vietnam." He said that American troops had shown themselves to be superb soldiers, adept at carrying out attacks against base areas and mounting sustained operations in populated areas. Yet, the operational initiative— decisions to engage and disengage—continued to be with the enemy.

North Vietnamese strategic buildup

By late 1966, however, North Vietnam began a buildup in the northwest area of the theater, in Laos, the southernmost part of the DRV, the DMZ, and in the northern part of the RVN. It has been argued whether these were plans at the operational level of war, to prepare for a strategy of attacking urban areas in early 1968, or if Vo Nguyen Giap believed that Khe Sanh, the main area of confrontation in the northwest, could be another Dien Bien Phu. The answer may be somewhere inbetween: Giap indeed wanted to draw American forces away from the coastal urban areas, but tried too hard for a victory at Khe Sanh.

Another alternative was that Giap was not looking for decisive results in either operational area, but simply attrition politically unacceptable to the U.S. In September 1967, he had written, in the PAVN journal, his assessment that the U.S. was faced with two unacceptable alternatives: invading the North or continue a stalemate. Invasion of "a member country of the Socialist camp" would enlarge the war, which Giap said would cause the "U. S. imperialists...incalculable serious consequences." As for reinforcements, "Even if they increase their troops by another 50,000, 100,000 or more, they cannot extricate themselves from their comprehensive stalemate in the southern part of our country."

1964

January 1964: Minh falls to Khanh

"Big" Minh was bloodlessly overthrown by Nguyễn Khánh on January 31, 1964. Khanh, at first, presented his government as more aggressive against the VC. At the time his government fell, the American embassy applauded the takeover, believing Minh had been too weak against the VC. The Pentagon Papers quote Douglas Pike's puzzlement:

Had the NLF leadership wished to do so, it could have used its impressive struggle machine to launch in the name of the Buddha a nation-wide struggle movement that conceivably could have ended with its long-pursued General Uprising . . . Knowledgeable Vietnamese attributed its refusal to act an unwillingness to involve itself in an alien struggle movement. The NLF and the communists, ran the argument, avoid activities over which they do not exercise total control. . . . The Buddhist leadership made it clear it did not seek NLF help since it wished at all costs to avoid the Communist stigma. Another popular explanation for the NLF's "sit-tight" policy during the Buddhist troubles was that the NLF was going to allow the bourgeois revolutionary forces to succeed in toppling Diem, after which it would capture the Revolution as the Kerensky Government was captured in the Russian Revolution. ... A slanderous but widely bandied explanation among Vietnamese at the time was that the NLF did not want Diem removed, that he and his brothers and sister-in-law were far more valuable to the NLF in office than out. In truth, the NLF posture during this period remains something of a mystery.

According to Robert McNamara, however, the Minh group had been following a strategy, but underestimated the insistence on the U.S. of having an anticommunist government. Minh described his group as noncommunist rather than anticommunist, which Minh described as an important distinction. They apparently sought incremental political improvements with the NLF, but this appears to have been the last chance, as coup after coup followed, of a neutralist solution. McNamara saw Ho Chi Minh also in favor of a neutral solution.

February: new government in Saigon

A coup against Khanh failed in early February, but he left the country within a few weeks, with the Armed Forces Council back in charge. Just before Khanh left, the Council did set up a new civilian government headed by Phan Huy Quat. INR saw the Quat government as evidence of a temporary stability between the military and the Buddhist, but one that could be broken by a power play of factions on either side.

May: Sabotage and attempted sabotage

A rather spectacular, although eventually repaired, underwater attack by VC divers disabled and partially sank, in the Saigon River, the USNS Card, a former small escort carrier being used as an aircraft ferry. The day after the May 2 sinking, an improvised explosive device injured 8 people at the dock.

There were incidents between ARVN and Cambodian forces through May and June, eventually leading to a UN investigation. Charges and countercharges include the Cambodians interfering with hot pursuit of a VC unit that entered Cambodia (5/7); Cambodian jets attacking RVN troops (5/12); RVN air attacks along the Cambodian border (6/5).

June 1964

Following additional combat along the SVN-Cambodian border, a UN investigating team left New York on the 21st.

September: Khanh allows civilian governmet

Under Khanh, the start of a civilian government, called the High Legislative Council, started in September, with Pham Khac Suu as head of state and Tran Van Huong as Premier and head of government. This Buddhist-dominated government may have wanted a neutral Vietnam as a solution. INR, however, did not believe this council would gain traction unless it was perceived as representative by both the populace and the military. Phan Quang Dan was ousted from the cabinet, and arrested, for suggesting more negotiation.

December 1964: Civilian government falls

Khanh dissolved the council in December, in the face of new demonstrations, although he temporarily retain Suu and Huong, dismissing them in December. Khanh, according to INR, created a new tension with the Buddhists that Huong had not, and also may have been approaching Hanoi much as he had accused Minh.

1965

To do this, he requested larger forces. which, after negotiations with McNamara, would constitute 47 U.S. maneuver battalions, plus supporting air and artillery. He would gain 27 battalions in 1966; the total allied force would consist of 150 ARVN and 47 US infantry battalions in 1966. On July 28, President Johnson would announce the large-scale commitment of another 44 battalions; at least 4 battalions, plus support elements, had been sent in the previous few months.

February 1965: VC attacks on U.S. facilities

On February 6, the VC attacked U.S. facilties at Pleiku, killing 8 and destroying 10 aircraft. President Johnson, on February 7-8, responded with the first specifically retaliatory air raid, Operation FLAMING DART (or, more specifically, FLAMING DART I), of the broader Operation ROLLING THUNDER plan, which had not yet officially started.

The Pleiku attack seems to have been a vital decision point for the U.S. While the introduction of U.S. ground troops had been discussed for years, there were no specific plans. Bundy's memorandum to Johnson about the attack, on 7 February, did not propose the introduction of combat troops.

Johnson made no public announcements, although the U.S. press reported it. The attack was carried out by U.S. Navy aviators from an aircraft carrier in the South China Sea. FLAMING DART II was a response to an attack on Qui Nhon on March 10. In response, initially unknown to the U.S., the North Vietnamese received their first S-75 Dvina (NATO reporting name SA-2 GUIDELINE) surface-to-air missiles, although civilian officials assumed they would not be used. In fact, the missiles were used, setting off upward spiral of air attack and air defense.

It must be emphasized that for most of the war, the bulk of the attacks on the North came, at first, from Navy carriers offshore. When the bombing escalated, they were joined by U.S. Air Force fighter-bombers flying from bases in Thailand. While there were occasional strikes on the DMZ and the southern part of the DRV from bases in the South, especially when South Vietnamese aircraft participated, the U.S. bases in the RVN primarily supported operations there. Da Nang was the primary South Vietnamese base for such strikes.

Bases in SVN, however, were accessible to the VC, by ground attack, or with rockets and mortars of only a few miles' range. As FLAMING DART progressed and the detailed planning for the major air escalation of ROLLING THUNDER, Westmoreland was concerned about the security of the exposed U.S. air bases in the south. On February 22, he sent his deputy, LTG John Throckmorton, to inspect the Marine aviation base at Da Nang; Throckmorton reported that a full Marine Expeditionary Brigade, with three infantry battalions and supporting elements, were needed to ensure its defense. Westmoreland, according to Davidson, believed a two-battalion MEB was more politically acceptable, but submitted that request.

The President approved sending two Marine battalions on February 26. Other than possibly Westmoreland, they were seen purely as defensive troops. Westmoreland denies assuming they would be available for missions outside the base. The Pentagon Papers suggest he did see a wider mission, but there is no strong evidence that he did.

Ambassador Taylor, a retired general with extensive combat experience, objected. His calculation was that one battalion would protect the base from any plausible direct VC ground attack, but that six, not three, battalions would be necessary to establish a sufficiently large area to prevent the VC firing on Da Nang with standard and easily portable 81mm mortars. The Joint Chiefs of Staff disagreed, and forwarded Westmoreland's request, with their agreement, on 26 February.

ROLLING THUNDER buildup, March

Shortly before Johnson approved the sustained Operation ROLLING THUNDER plan on March 13, the Da Nang security force arrived on March 8. in response to Westmoreland's request of February 22 reflecting a concern with VC forces massing near the Marine air base at Da Nang, 3500 Marine ground troops arrived, the first U.S. large ground combat unit in Vietnam.

Assistant Secretary of Defense for International Affairs sent a key memo to McNamara. His "70%" justification for staying in Vietnam was to protect U.S. reputation, with a lesser role of preventing major Chinese intervention, the latter not having been documented. Essentially, he saw no way to extricate the U.S. The memo also said there was a "50% chance of coup within 3 weeks," and, SVN has been cut in two with GVN control in north reduced to enclaves.

President Johnson ordered Chief of Staff of the Army GEN Harold Johnson to assess the situation, already doubting the air offensive before it seriously began. GEN Johnson reported, in Vietnam between March 5 and 12, reported back on 14 March. He was seriously concerned about the situation, and proposed external forces be brought in to free the ARVN for offensive action because "what the situation requires may exceed what the Vietnamese can be expected to do." He proposed a U.S. division be sent preferentially to the Central Highlands (II Vietnamese corps area; Kontum, Pleiku, and Darlac provinces) or to the Bien Hoa/Tan Son Nhut area nearer to Saigon. McNamara, however, did not think such action would make enough ARVN troops available and preferred that a Republic of Korea division be sent rather than U.S. troops. GEN Johnson also suggested a four-division force be raised under the SEATO treaty and used to block infiltration.

GEN Johnson said a decision was needed "now to determine what the Vietnamese should be expected to do for themselves and how much more the U.S. must contribute directly to the security of South Vietnam." Secretary McNamara noted in the margin: "Policy is: anything that will strengthen the position of the GVN will be sent..."

Carrot and Stick, April

Johnson's main public announcement at the time, however, was an April 7 speech, in which he offered economic support to North Vietnam, and Southeast Asia in general, if it would stop military action. This offer was quite in keeping with his goals for development, the Great Society, in the United States, and was likely a sincere offer. That he saw such an offer as attractive to the enemy, however, is an indication of his lack of understanding of the opposing ideology.

More elaboration of the proposal was in National Security Action Memorandum 329 This initially classified (but at the lowest level) document, among other things, asked for specific recommendations of a "reviews of the pros and cons" of increasing U.S. aid even before a regional development program started.

The Director of Central Intelligence, wrote to McNamara and others that the ROLLING THUNDER campaign was not a serious deterrent to the DRV, and warned against putting more U.S. troops into combat roles. McCone said that this would merely encourage the Soviets and Chinese to take a low-risk course of supporting infiltration.

As these proposals were made to the North, on 13 April 1965, joint RVN-US discussions agreed that the ARVN force levels were inadequate. The manning level was increased, to increase RVN infantry battalions from 119 to 150. The new battalions were generally added to existing regiments, to avoid the need of creating more headquarters units. By the end of 1965, twenty-four were either in the field or in training areas.

In April, Johnson authorized the deployment of an additional two Marine battalions and up to 20,000 support personnel. Again without public announcement, he changed the rules of engagement to permit the Marines to go beyond static defense, and to start offensive sweeps to find and engage enemy forces.

RVN reverses in May

A VC unit, estimated to be in two-regiment strength, fought the Battle of Song Be, the capital of Phuoc Long province, about 100 miles from Saigon, on 11 May. Song Be was primarily defended by irregular ARVN units, although supported by a Special Forces team and several miscellaneous units. An unprecedented amount of air support, including the first use of a company-sized armed helicopter unit, allowed a successful defense. Higher command, however, was concern that this large a VC unit could take an initiative. Much farther in the north, later in the month, they ambushed an ARVN force in the north, near Quang Ngai, badly hurting ARVN relief troops and leaving two battalions combat ineffective.

Westmoreland obtained Taylor's agreement on a plan for reinforcement. It had three phases, the first two establishing security for Allied bases and then an offensive strategy, beginning with enclaves on the cost, and moving inland.

The first phase extended the security perimeter of the bases so that the facilities were out of range of light artillery. In the second stage, the U.S. forces, in coordination with the RVN, would make deep patrols and limited offensives, still centered on the bases, to pre-empt direct threats.

Phase III defined "Search and destroy plus reserve reaction operations." Westmoreland proposed improving the security of coastal enclaves, then, as a second phase, patrolling from those enclaves. Once the coastal areas were being patrolled, the next two phases would repeat the process inland: establish bases, then patrol from them.

Westmoreland assumed he would have III Marine Expeditionary Force, the new airmobile division, a Republic of Korea division replacing the Marines in central Vietnam, and the 173rd Airborne Brigade for the Bien Hoa/Vung Tau area near Saigon. Early, CINCPAC had objected to the use of the 173rd, since it was the primary strategic reserve for Pacific Command.

Further ARVN deterioration

Westmoreland, on June 7, sent a message to CINCPAC that a VC summer offensive was underway, not yet at its full potential, both to destroy RVN forces and isolate (but not hold) key towns. He doubted the South Vietnames capability to cope was in grave doubt, largely due to recent troop losses.

On June 10, the VC made another two-regiment attack on Dong Xoai, north of Saigon, using one regiment against the town and Special Forces camp, while preparing an ambush for an ARVN relief force with the other. The area also held a U.S. aviation unit, advisory team, and Naval Construction team; the fighting was sufficiently savage that two Medals of Honor were bestowed on U.S. troops, one posthumously.

The VC ambushes were extremely effective against ARVN relief forces, which were committed one battalion at a time, until the ARVN ran out of reserves. Among the forces destroyed was the 7th Airborne Battalion, one of the best units in the ARVN.

The civilian government under Premier Phan Huy Quat and Head of State Phan Khac Suu, both Buddhists, had been challenged by Catholics, Cao Dai and Hoa Hao. There were also accusations that the military forced them out for entertaining a neutralist solution. While they stayed in office as "caretakers", power returned to the military on June 12. Air Force Marshal Nguyen Cao Ky became the effective center of power.

McNamara proposes escalation

On July 1, both George Ball and William Bundy, of the U.S. Department of State, sent memoranda to President Johnson saying the war could not be won on U.S. terms; they proposed different exit strategies. At Defense, McNamaara agreed the situation was worse, but believed the situation might be retrieved: "The situation in SVN is worse than a year ago (when it was worse than a year before that). After a few months of stalemate, the tempo of the war has quickened. . . . The central highlands could well be lost to the NLF during this monsoon season. Since June 1, the GVN has been forced to abandon six district capitals; only one has been retaken...The odds are less than even that the Ky government will last out the year. Ky is "executive agent" for a directorate of generals."

McNamara saw the correlation of forces between the ARVN and the VC is quite unfavorable. "The Govt-to-VC ratio overall is now only a little better than 3-to-1, and in combat battalions little better than 1.5-to-1." A historical rule of thumb for counterinsurgency has been that a 10 to 1 ratio is desirable, but, like all rules of thumb, it is not applicable to all situations. Even a critic of that generalization, "indeed, that ratio was often cited by critics of the U.S. policy in Vietnam", who cite a number of other revolutionary wars where the insurgency was defeated by less overwhelming ratios (e.g., Eritrea against Ethiopia) or where an acceptable goal was partition (e.g., Second Sudanese Civil War), cite the conventional wisdom as primarily relevant to situations of ideological insurgency against a central government, such as the Communist takeover of Vietnam, where the insurgents want complete victory. The current U.S. Army doctrine on counterinsurgency also recognizes there is no simple ratio, "During previous conflicts, planners assumed that combatants required a 10 or 15 to 1 advantage over insurgents to win. However, no predetermined, fixed ratio of friendly troops to enemy combatants ensures success in COIN...A better force requirement gauge is troop density, the ratio of security forces (including the host nation’s military and police forces as well as foreign counterinsurgents) to inhabitants...Twenty counterinsurgents per 1000 residents is often considered the minimum troop density required for effective COIN operations; however as with any fixed ratio, such calculations remain very dependent upon the situation." None of these sources, however, see a 3:1 to 1.5:1 as favorable.

McNamara also observed that the Administration's approach to air war against the North, Rolling Thunder, had not " produced tangible evidence of willingness on the part of Hanoi to come to the conference table in a reasonable mood. The DRV/VC seem to believe that SVN is on the run and near collapse; they show no signs of settling for less than complete takeover."

Campaigns for Central Vietnam

North Vietnam developed a new plan to move from the Ho Chi Minh trail in Cambodia, in central Vietnam (i.e., ARVN II Corps tactical zone), with a goal of driving through to the seacoast, splitting South Vietnam in half. For this large operation, the PAVN created its first division headquarters, under then-brigadier general Chu Huy Man. This goal at first seemed straightforward, but was reevaluated when major U.S. ground units entered the area, first the United States Marine Corps at Danang, and then the [[1st Cavalry Division|1st Cavalry Division (Airmobile), the "First Cav". In particular, the PAVN were not sure of the best tactics to use against the air assault capability of the 1st Cav, so BG Man revised a plan to bring to try to fight the helicopter-mobile forces on terms favorable to the North Vietnamese. They fully expected to incur heavy casualties, but it would be worth it if they could learn to counter the new U.S. techniques, inflict significant casualties on the U.S. Army, and, if very lucky, still cut II CTZ in half. That planned movement was very similar to the successful PAVN maneuver in 1975.

The resulting campaign is called the Battle of the Ia Drang, with a followup at the Battle of Bong Son, but Ia Drang actually had three major phases:

• PAVN attack on the Plei Me CIDG camp, ambushing the expected heavy rescue force and possibly attracting the 1st Cav,
• Putting simultaneous pressure on Plei Me and Pleiku, so II CTZ would need to call in U.S. reinforcements; this is what became the Battle of the Ia Drang in popular Western terms, but has been called either the U.S. Battle of the Ia Drang or the Pleiku Campaign,
• An ARVN counteroffensive against the PAVN troops retreating into Cambodia, an action fought by the ARVN Airborne Brigade with U.S. air and artillery support.

In the larger Battle of Bong Son approximately a month later, which extended into 1966, 1st Cav drew their own lessons from what they believed the PAVN developed as countertactics to aiir assault, and used obvious helicopters to cause the PAVN to retreat onto very reasonable paths to break away from the Americans — but different Americans had silently set ambushes, earlier, across those escape routes.

1966

1966 was the year of considerable improvement of command relationships, still under Westmoreland, for what Westmoreland considered the less interesting "other war" of rural development. There were frequent changes of names of aspects of this mission, starting in 1964, but eventually, the GVN and US agreed on the term Revolutionary Development (RD), which was to continue in a variety of development activities. The term, apparently coined by Premier and general Nguyen Cao Ky, was agreed to be defined as

RD is the integrated military and civil process to restore, consolidate and expand government control so that nation building can progress throughout the Republic of Vietnam. It consists of those coordinated military and civil actions to liberate the people from Viet Cong control; restore public security; initiate political, economic and social development; extend effective Government of Vietnam authority; and win the willing support of people toward these ends.

"Search and Destroy" gave way after 1968 to "clear and hold", when Creighton Abrams replaced Westmoreland.

Strategic

Pacification

Westmoreland was principally interested only in overt military operations, while Abrams looked at a broader picture. MACV advisors did work closely with 900,000 local GVN officials in a well-organized pacification program called CORDS (Civil Operations and Revolutionary Development.) It stressed technical aid, local self government, and land distribution to peasant farmers. A majority of tenant farmers received title to their own land in one of the most successful transfer projects in any nation. On the other hand, hundreds of thousands of peasants entered squalid refugee camps when CORDS moved them out of villages that could not be protected.

In the Phoenix Program (part of CORDS with a strong CIA component) GVN police identified and arrested (and sometimes killed) the NLF secret police agents engaged in assassination.

Political

On January 15, Premier Ky announced, at the 2nd Armed Forces Congress in Saigon:

• There will be a national constitutional referendum in October
• General elections will be held in 1967

On February 20, Deputy Ambassador Porter became the overall chief of US participation in Revolutionary Development, raising its priority vis-a-vis the concept of engaging the main force.

Much of the year, however, was dominated by the Buddhist crisis.

The September 11, 1966 elections took place, with a 80.8 percent turnout. INR interpreted this not so much as support for the GVN, but more of the absence of a serious challenger to Ky, a situation that changed in 1967.

Phan Khac Suu was elected Speaker of the GVN Constituent Assembly on October 26.The GVN Constituent Assembly approved, on December 23, the first three articles of the new constitution, providing for popularly-elected President, and a Prime Minister and Cabinet appointed by the President. Elections, indeed, were held in 1967.

Military Events

The year was filled with large sweep operations, including individual U.S., ARVN, and Korean forces of division and sometimes larger size, as well as use of multinational force use. VC attacks ranged in size from local bombings to multi-regimental operations, and use of longer-range artillery.

Starting on the 20th, the non-Communist forces held an 84-hour ceasefire for Tet, which was the culmination of a psychological warfare program to encourage Communist defections under the Chieu Hoi program. MACV annouced 106 Communist violations of the truce.

Starting in mid-February, patrols detected indications of a pending VC attack against the A Shau Special Forces camp, whose mission was surveillance of infiltration from the nearby Laotian border. Continuous attacks on 9-10 March overran the camp, with a disorderly retreat losing several helicopters and resulting in a number of friendly personnel missing in action.

In April, ROLLING THUNDER units struck significantly closer to Hanoi and Haiphong than they ever had done, and the DRV Air Force responded with their first MiG-21 use.

There was an increasing intensity to use air power in Cambodia and Laos, accelerating in July. In some, but not all cases, the Cambodian or Laotian governments were secretly consulted, but in other cases, U.S. aircraft, especially B-52 bombers acted at direct U.S. orders.

According to Giap, the PAVN began, in late 1966, intensifying their actions in Laos, the Demilitarized Zone, and the southern area of the North, with the intention of drawing attention from the more populated area. While the true amount of long-term planning has been argued, he described it as a preparation for the Tet offensive in early 1968.

1967

General Nguyen Van Thieu (1923-2001), a Catholic, became president (in office 1967-75). The NLF failed to disrupt the national legislative election of 1966, or the presidential elections of 1967, which consolidated Thieu-ARVN control over GVN. Thieu, however, failed to eliminate the systematic internal inefficiencies and corruption the ARVN.

Ground combat

In 1967, the NVA organization in the northwest was under two Military Regions (MR), MR-4 north and south of the DMZ, and MR-5 (also known as MR-S) for Communist units in the northern part of South Vietnam. Essentially, the MR-4 command was conventional while MR-5 was guerilla. MR-4 commanded five divisions north of the DMZ, three operational, one reserve, and one recovering from battle.

Air war

In April, attacks began on all but one of the North Vietnamese fighter airfields; Phuc Yen, the international airport, remained off limits. Approximately half of the North Vietnamese fighters were shot down in May.

1968

Spring

In April and May, the North Vietnamese 320th Division fought the U.S. 3rd Marine Division i the area north of Dong Ha, resulting in heavy NVA casualties.

Summer

Starting in June, Marine operations made more extensive use of artillery fire support bases, a variant on typical Marine Air-Ground Task Force doctrine that tends to use air rather than substantial artillery. The 3rd would usually colocate an infantry battalion command post with the firebase, from which the infantry companies would move by foot or helicopter.

The 320th, in August, again moved against the 3rd, south of the Ben Hai River and north of Route 9, between Cam Lo and the Rockpile.