A variety of evidence from the Nixon tapes and from transcripts of meetings with foreign leaders is cited to support this theory, including Henry Kissinger's statement before the 1973 Paris Peace Accords that "our terms will eventually destroy him"[1] (referring to South Vietnamese president Nguyễn Văn Thiệu).
Already by late 1970 or early 1971, President Richard Nixon and his National Security Advisor Henry Kissinger "effectively abandoned the hope of a military victory" in the Vietnam War.
[5] The idea of a decent interval was absent from public debate during the Nixon years and originally advanced in a 1977 book of the same name by former CIA analyst Frank Snepp.
[7] What Snepp was most outraged over was the haste with which the Americans pulled out in April 1975, abandoning many key South Vietnamese allies and intelligence assets to their fates.
[9] The first sign of the strategy appears in the Nixon tapes on 18 February 1971, Kissinger stated that after a peace agreement was concluded, "What we can then tell the South Vietnamese—they've got a year without war to build up."
[11] In his first secret meeting with Zhou Enlai in 1971, Kissinger explained that the United States wanted a full withdrawal, the return of all POWs, and a ceasefire for "18 months or some period."
"[14] Historian Jeffrey Kimball supports the decent interval theory and promoted it in various books, including The Vietnam War Files (2004)[15] and Nixon's Nuclear Specter (2015).
In a 2003 paper, Finnish historian Jussi Hanhimäki argued that from the summer of 1971 to the conclusion of the Paris Agreements in January 1973 Kissinger tried to "sell" a peace agreement to his Soviet and Chinese interlocutors by stressing the American willingness to accept a "decent interval" solution: that is, the United States would not reenter the war provided that the collapse of the South Vietnamese government did not occur immediately after the last US ground troops returned home.
[20]According to Japanese historian Tega Yusuke, writing in 2012, decent interval "is becoming the standard explanation" because South Vietnam in fact collapsed in 1975.
[9] Based on newly declassified documents, in 2001 Larry Berman wrote a book, No Peace, No Honor in which he argued that Nixon actually planned for a permanent war in Vietnam, rather than a decent interval before defeat.
According to Kadura, the "decent interval" concept has been "largely misrepresented", in that Nixon and Kissinger "sought to gain time, make the North turn inward, and create a perpetual equilibrium" rather than acquiescing in the collapse of South Vietnam.