John Bolton, the State Department's top international security official, will leave the post in the second Bush administration and be replaced by an arms control specialist at the National Security Council, a senior U.S. official said Friday. Bolton, who promoted programs to slow the spread of sophisticated weapons technology around the world, has served as undersecretary of state for arms control and international security in the four years of the first Bush administration. Meanwhile, an administration official said that Nicholas Burns, U.S. ambassador to NATO, is slated for the State Department's third-ranking position, under secretary for political affairs. Burns, a...