The Pentagon leadership has warned the armed services that budget cuts may threaten major weapons programs, including the next generation of fighter planes and submarines. In a memo obtained by reporters, Deputy Defense Secretary John Deutch warns that money appropriated for defense is likely to be tight from 1996 to 2001. Some endangered programs: the Air Force F-22 fighter, the Army's Comanche helicopter and the Navy and Marines' V-22 Osprey. "This doesn't mean that they'll be cut. It's just to say that these are not sacred cows," Defense Secretary William Perry said today.