As shown by the now fully declassified " Pentagon Papers," the United States, which began its involvement in Vietnam in 1945, gradually increased its military commitment to the defense of South Vietnam to the point that President Lyndon B. Johnson dispatched half a million troops to Southeast Asia. While responsible for dramatically escalating US military intervention into the Vietnam conflict, President Johnson was also the first president to seek a negotiated end to the war. Between 1965 and 1967, US officials repeatedly, and unsuccessfully, attempted to initiate serious peace talks with North Vietnam. On May 13, 1968, while the US continued its bombing campaign against North Vietnam, the United States, South Vietnam, and North Vietnam finally began formal talks in Paris. The opening positions of the negotiation were:
- North Vietnam demanded "unconditional cessation of US bombing raids and all other acts of war so that talks may start."
- The United States was willing to halt the bombing but it demanded a reciprocal de-escalation from the North Vietnamese.
The North Vietnamese rejected those demands and the talks were deadlocked. Meanwhile, the war continued. In late 1968 with the talks still deadlocked, President Johnson became open to a bombing halt as a way of encouraging a political settlement. This change also reflected some domestic pressure to halt US air offensive. Some of the pressure was coming from Democratic Party leaders who wanted to help Vice President Hubert H. Humphrey's campaign. In Paris, US chief negotiator Averell W. Harriman got North Vietnam to accept a cease-fire in return for an end to US bombing, and to allow the South Vietnamese to take part in the negotiations for the first time. There was little progress, however, because in reaction to the "Bombing Halt," South Vietnam's president, President Nguyen Van Thieu, refused to let his government participate in the negotiations, opting instead to see who won the US presidential elections in November. People claiming to speak for the Republican nominee, former Vice President Richard Nixon, had promised Thieu that a Nixon administration would be a more dependable ally of South Vietnam.
In the 1968 campaign, Richard Nixon had promised that, if elected, he would seek "peace with honor" in Vietnam and pull US troops out of the increasingly unpopular war. In his first three years in office, President Nixon instituted a phased withdrawal of US troops and announced a formal policy of "Vietnamization." Building upon what the Johnson administration had started in 1968, the Nixon administration stated a goal of making the Vietnamese increasingly responsible and capable of their own defense. Public controversy arose, however, because while the President vowed to decrease the country's commitment to a land war in South Vietnam, he broadened the scope of US military involvement in the region to include air and land attacks against North Vietnamese positions in neutral Cambodia.
Although the US and North Vietnam continued secret negotiations under the new president, there was little progress. US and Vietnamese negotiating positions remained virtually the same as they had been in 1968. Geopolitical changes outside of Southeast Asia in 1972, however, gave the Nixon administration real hope for a diplomatic exit from the Vietnam conflict. President Nixon's decision to engage the People's Republic of China [PRC] as a diplomatic equal roiled the Cold War alliance structure. The Soviet's, perhaps fearing a ganging up of Washington and Beijing, reacted to the President's announcement in mid-1971 that he would be visiting China the next year, by sending signals that they wanted a thaw in superpower relations. There was progress, for example, in long-stalled strategic arms negotiations. Regardless of Beijing and Moscow's motives for better relations with the United States, by the summer of 1972 the Nixon administration had reason to hope that the Union of Soviet Socialist Republics [USSR] and the PRC might see it in their interests to pressure North Vietnam into a negotiated settlement.
This hopeful change in the international diplomatic scene coincided, however, with yet another escalation in the Vietnam conflict. In May 1972, the North Vietnamese launched a massive spring military offensive against the South. And, in response, on May 8, 1972 President Nixon authorized a stepping up of the air war against North Vietnam codenamed Operation Linebacker.
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