There have been at least four major false alarms, the most recent in 1995, that resulted in the activation of nuclear attack early warning protocols. They include the accidental loading of a training tape into the American early-warning computers; a computer chip failure that appeared to show a random number of attacking missiles; a rare alignment of the Sun, the U.S. missile fields and a Soviet early-warning satellite that caused it to confuse high-altitude clouds with missile launches; the launch of a Norwegian research rocket resulted in President Yeltsin activating his nuclear briefcase for the first time.