Japan has confirmed the existence of a secret cold war deal allowing the transit of nuclear-armed US vessels through its ports. The move by a government-appointed panel ends decades of official denials. The government said that the move was aimed at increasing transparency. The deal was sealed in the 1960s between US and Japanese diplomats. The two countries agreed that the transit of nuclear arms through ports did not constitute the introduction of weapons into Japan, and so did not require prior consultation on the US side.