A WEEK before Bob Hawke dumped support for a US missile test, Federal Cabinet signed off on a plan to maintain the deal and avoid political fall-out by blaming Malcolm Fraser.

Secret Cabinet documents, released today by the National Archives of Australia, show Mr Hawke and his senior security ministers discussed the US plan to fire intercontinental ballistic missiles into the Pacific Ocean.

The crisis meeting, held on January 29, 1985, ended in a decision to blame Mr Hawke's predecessor, Mr Fraser, who in 1981 had agreed with US requests to send two missiles into the ocean about 220km from Tasmania.

In 1983 Mr Hawke had quietly agreed to continue backing the program, but Cabinet did not appear to have met until 1985 over the issue.

Marked "SECRET", the documents show the security committee agreed to remain tight-lipped about the crisis until forced to speak.

"In the event of circumstances requiring the Government to explain its position on the MX missile test program, the Government would publicly confirm that... upon coming to office it had been confronted with an undertaking given by its predecessor," documents say.

The decision to honour that commitment was made "only after the Prime Minister had secured US agreement to the transfer of the splash-down zone out of Australian EEZ into international waters".

And it was decided Mr Hawke would tell the US this support "would not constitute a precedent" for further requests.

A week later, before a visit to Washington, Mr Hawke sensationally backed out of the agreement with the US.

Mr Hawke told News Ltd his support for the testing was "in the depths of the Cold War".

"You had an hegemonistic Soviet Union that was spreading its influence and domination in a great arc going from southern Africa... into the Middle East and down to Vietnam," he said.

"These weren't play games, this was real stuff.

"It was absolutely appropriate in my judgement, and those of my immediate colleagues, that the United States should also be able to test its missiles."

Mr Hawke said the caucus revolt he faced was placated after he visited the US.

He said US Secretary of State George Shultz, a close friend, had told him it "wasn't absolutely essential to use the Australian facilities" and he didn't hesitate to withdraw support.

"We went from boiled lollies to chocolates because from a situation where we had a lot of division, I got back and went to discuss things in Caucus and for the first time got a unanimous vote in Caucus supporting the general security position I had adopted," he said.

"There was a lot of hysteria around in those times around the uranium mining and nuclear power and all this sort of thing."