The documents were declassified amid reports that the Obama Administration is considering a civil nuclear deal with Pakistan.
Declassifying a number of documents, the National Security Archive (NSA) said that the Reagan administration had an internal debate over policy towards Pakistan's developing nuclear capability.
The debate led to a letter from Reagan to Pakistani dictator Muhammad Zia-ul-Haq, never before published, asking for a commitment to low levels - five per cent - of nuclear enrichment.
Through the 1980s, the war in Afghanistan had priority over Pakistan's nuclear programme and Reagan and his top advisors did not want to take any action that would jeopardise Pakistan's role as a conduit for US aid to the Mujahadin, NSA said in a media release.
More From This Section
In his letter dated September 12, 1984, Reagan wrote of his "appreciation" that Zia had made the assurance on five per cent, further stating that higher levels of enrichment above five per cent "would have the same significance" as the other nuclear activities, such as unsafeguarded reprocessing which "I had personally discussed with you and would have the same implications for our security programme and relationship."
NSA said the Soviet war in Afghanistan, and US support for Pakistan's aid to the mujahidin, was the context for Reagan's points on nuclear proliferation.
That Afghanistan was the overwhelming priority was also evident in draft talking points that were prepared for Ambassador Hinton: Washington remained "fully committed to supporting you in our common effort."
The talking points went on at some length about nuclear issues, including the importance of Pakistani assurances and the need for Indian-Pakistani dialogue, but they included no reference to penalties if Pakistani cooperation was found wanting, NSA said.