As North Vietnam was invading South Vietnam during spring 1975, the U.S. ambassador in Saigon, Graham Martin, reported that North Vietnam was claiming they had a secret agreement with Washington, saying of North Vietnamese officials, “they would love to have you sit down with Le Duc Tho in order to confirm the rumors they are spreading through South Vietnam that this offensive is part of a deal they we have made with them” (see Document 9). Coincidentally, during May 1972, Kissinger did appear to have made just such a secret deal with Brezhnev. In return for the USSR cutting its arms exports to North Vietnam, the United States agreed to allow North Vietnam to invade the South a year-and-a-half after the peace treaty was signed and went into force.

If the goal of the Vietnam War was to divide the USSR and China, that goal absolutely succeeded on 2 March 1969. When holding U.S.-Soviet discussions in Moscow on how best to end the war in Vietnam, a deal appears to have been struck. During secret talks between Nixon, Brezhnev and Kosygin in May 1972, Kosygin reassured Nixon “there is not a single ship on the way to Vietnam now carrying military equipment—not one shell—only flour and foodstuffs, no armaments whatever” (see Document 10). Cutting North Vietnam off from Soviet weapons was clearly intended to put pressure on Hanoi to come to terms with Washington.

In return, the U.S. government made its own offer. If the USSR would help convince Hanoi to sign a peace agreement, preferably before Nixon's second term in office began, then after a certain amount of time—in this case 18 months—the U.S. government “would be agreeable to the Vietnamese doing whatever they want” (see Document 11).

Without Soviet backing, Hanoi had little choice but to open peace talks with the United States. A peace agreement ending the Vietnam War was in fact signed in Paris on 27 January 1973, just a week after Nixon was inaugurated for his second term. By this point Brezhnev had certainly passed on Nixon's offer. Almost exactly a year-and-a-half after the peace agreement went into effect during summer 1973, North Vietnam did successfully invade South Vietnam during spring 1975, and the United States did not intervene to oppose it.