NEW : About 100 personnel are participating in the exercise , Russia says . U.S. has not yet seen if Russian forces are prepping for a move into Ukraine . But a senior administration official says military officials are raising concerns . ` ` let 's see no provocative moves by anyone , '' U.S. defense official says .
NEW : About 150,000 personnel are participating in the exercises , Russia says . U.S. has not yet seen signs Russian forces are prepping for a move into Ukraine . But a senior administration official says military exercises are raising concerns . `` Let 's see no provocative actions by anyone , '' U.S. defense secretary says .