The American presidential election came and went, but the negotiating deadlock remained. Tantalized and frustrated by the settlement at their fingertips, Nixon and his advisers decided on a final stratagem to end the war. To allay Thieu's fears, they ordered a massive quick infusion of aid to the South and promised to continue support after the agreement was signed; meanwhile, to get the North Vietnamese back to the table, they ordered devastating airstrikes.
The "Christmas bombing" succeeded in compelling Hanoi's assent while helping to cover up Washington's insistence that Saigon accept an agreement similar to the one negotiated in October. Thus pulling along a reluctant ally and enemy, the United States signed the Paris Accords on Jan. 27, 1973, formally extricating itself from the Vietnam War.
Nixon's private guarantee to Thieu in November had been clear: "You have my absolute assurance that if Hanoi fails to abide by the terms of this agreement it is my intention to take swift and severe retaliatory action." He repeated the pledge in January. Later on, he and Kissinger argued that they had always intended to carry out these promises and fully expected they would be able to do so—but they could not because Congress barred the way.
"Soon after the agreement was signed," Kissinger wrote in his memoirs, "Watergate undermined Nixon's authority and the dam holding back Congressional antiwar resolutions burst." He claimed, "The war and the peace ... won at such cost were lost within a matter of months once Congress refused to fulfill our obligations."
It is true that Congress restricted U.S. operations and cut aid to the South, and these moves did indeed facilitate the eventual Northern victory. But these events were entirely predictable; the settlement the Nixon administration negotiated left the South vulnerable to future attacks. To the American public, the most important fact about the Paris Accords was that American troops and prisoners came home; it was precisely because a guarantee of renewed U.S. military intervention would have been so controversial that Nixon had to make his promises to Thieu in secret.
After January 1973, as before, Vietnamese belligerents on both sides kept up military pressure and prepared for a final showdown. But the American public tried to blot the war out of its consciousness—and largely succeeded. A consensus formed that the United States should not re-engage and should reduce its remaining involvement still further. Reflecting this, in June 1973, Congress ordered all U.S. military operations in Indochina to cease by the end of the summer, and in November it passed the War Powers Act.
Congress also cut U.S. aid to Saigon, from about $2.3 billion in 1973 to about $1 billion in 1974 and still less after that. Together with the 1973 oil crisis, which crippled what remained of the South Vietnamese economy, this made it difficult for Saigon to use the expensive high-tech war machine it had been given. So, even if Watergate never occurred, it would have been difficult for the Nixon administration to counter Northern attacks in any substantial way. That said, the developing Watergate scandals did eliminate whatever freedom of action the administration had left.
In late 1974, the North Vietnamese leadership calculated that American re-entry to help the South was unlikely, and they launched a campaign to win the war once and for all. Their initial victories in the spring of 1975 came easily. At this point, Kissinger, now Gerald Ford's secretary of state, recommended a final desperate burst of U.S. help, but the new president acquiesced to public and congressional objections.
On April 23, Ford told a cheering crowd of students that national pride could not "be achieved by refighting a war that is finished as far as America is concerned." Thieu outlasted Nixon by eight months; on May Day 1975, Communist soldiers hoisted their flag above the erstwhile capital of South Vietnam, now Ho Chi Minh City.
It has been said that history doesn't repeat itself, but it rhymes. On the Vietnam timeline, in Iraq today the Bush administration is roughly where the Nixon administration was in 1969-70: Washington has been unable to find or create a strong and dependable local ally, the American public has lost faith, and working-level officials are desperately casting about for ways to pull off a retreat instead of a rout. One key difference, however, is that Bush himself seems to be stuck where Johnson was back in 1968—unwilling to accept that his war is in fact lost or that the game is not worth the candle. He has two years left on his personal clock. With another electoral season fast approaching, his Congressional counterparts and would-be successors have less.