Poland has opened up the secret files of the former Warsaw Pact, including documents confirming the alliance's readiness to launch nuclear attacks on European cities in the event of war.

Defense minister Radek Sikorski authorized the transfer of the files to the National Remembrance Institute, a center where they will be available for study by historians. The files include a map of planned Soviet and other Warsaw Pact troop movements and the cities targeted for nuclear strikes in the event of war between the Soviet-led alliance and NATO.

The minister said the files will provide valuable information about the 1968 Warsaw Pact invasion of Czechoslovakia that crushed that country's communist liberalization movement under the party chief Aleksander Dubcek.  It also could prove embarrassing to former Polish President Wojciech Jaruzelski, who imposed martial law in 1981 in efforts to crush the independent Solidarity Trade Union.

Some information for this story provided by Reuters and AP.