Prosecutors at the Tokyo war crime trials in 1945 closely looked into the delay in delivering the U.S. president's letter to Emperor Hirohito on the eve of war, apparently to establish that the foreign minister was to blame for failing to stop Japan's attack on Pearl Harbor, according to Japanese diplomatic records declassified Thursday.

The International Prosecution Section at the Allied Forces' General Headquarters appears to have believed that if President Franklin D. Roosevelt's telegram, sent two days before the start of the Japan-U.S. war in 1941, was delivered promptly to the Emperor, he could have called off the attack, the records showed, citing a Foreign Ministry official questioned by the IPS.

Roosevelt sought to avert war by sending the letter dated Dec. 6, 1941.