Republican presidential candidate Bob Dole returned to active campaigning, introducing a national defense theme to his stump speech in Indianapolis. He also blasted President Clinton for going too easy on Japan in trade talks. The Senate leader said the U.S. is defenseless against missile attacks because Clinton vetoed the deployment of a $5-billion ballistic missile defense system. "I believe they are playing with fire," Dole said. "The threat to our citizens is very real" from missile technologies in China, North Korea and Russia. The administration, however, says that the threat does not justify the cost of putting the system in operation.