Specifically , they agreed to notify each other immediately in the event of an accidental , unauthorized or unexplained incident involving a nuclear weapon that could increase the risk of nuclear war .
The countries also agreed for the first time when the line should be used .
They agreed to notify each other immediately in the event of an accidental , unauthorized or unexplained incident involving a nuclear weapon that could increase the risk of nuclear war .
The countries also agreed for the first time when the line should be used .