'US had plans for full nuclear response against Russia, China'

But this policy was changed by the then President Lyndon Johnson in October 1968, according to a previously top secret document published today for the first time by the National Security Archive.

Prior to Johnson's decision, instructions for the emergency use of nuclear weapons that both he and his predecessors had previously approved stipulated a full-scale nuclear counter-attack even if the initial strike were conventional, or the result of an accident, and both Communist giants would be targeted regardless of whether either of them had launched the first strike, the National Security Archive said it a statement.

According to the Archive, this new information is contained in a record of a meeting between Johnson and his top national security advisers on October 14, 1968.

At the meeting, Johnson's military and civilian aides unanimously recommended that the standing orders, known by the code-name "Furtherance," be revised substantially in order to reduce the inherent risks involved.

The changes included providing instructions to commanders to respond to a conventional attack with conventional weapons--an implicit "no-first use" nuclear policy.

At the session, speaking of the new approach, National Security Advisor Walt Rostow advised Johnson: "We think it is an essential change. This was dangerous."

The entire Joint Chiefs of Staff concurred.

The meeting record, marked "Eyes Only for the President", was released to the National Security Archive in late November 2012 under a Mandatory Declassification Review appeal to the Interagency Security Classification Appeals Panel (ISCAP), nine years after the filing of the original request.

The declassified transcript offers important insights into the still-heavily shrouded subject of pre-delegation of nuclear weapons use.

The meeting record is accompanied in today's posting by several related items that provide contemporary context to the subject matter.