By Adam Easton

BBC News, Warsaw



The minister said he was shocked by what the files contained

Radoslaw Sikorski said the files, which had remained secret until now, will be open to historians at the state-run Institute of National Remembrance.

The institute investigates war crimes in the Communist era.

The archive reveals details about the Soviet invasion of Czechoslovakia in 1968 and the imposition of martial law in Poland in 1981.

Nuclear strike

During the Cold War, the threat of nuclear conflict constantly hovered over Europe.

For 36 years the Warsaw Pact squared up against the Western military alliance, Nato.

For years Soviet strategists believed war with the West was likely and had a long standing plan to launch a pre-emptive nuclear strike.

During a news conference, the new Polish defence minister, Mr Sikorski, described how Poland would have been affected by such a war.

He produced a map showing where the planners thought missile strikes would hit.

He said it had been a shattering experience for him to discover Poland was being asked to participate in an operation which would lead to the nuclear annihilation of the country.

Mr Sikorski said almost all of the 1,700 files would be handed over to historians.

Without going into details, he said they offer valuable knowledge about the Warsaw Pact invasion of Czechoslovakia in 1968.

The military alliance was dissolved in 1991, following the collapse of Communism.

Eight years later, Poland and other former Soviet Bloc countries joined Nato.