President George W. Bush wants to bolster the multinational fight in Afghanistan by reminding NATO allies that the war is in their interest - and by persuading them to send more troops into battle. Bush was on his way Monday to Ukraine, the start of a trip that will also lead to Romania, Croatia and Russia. Beyond Afghanistan, Bush is trying to score a breakthrough on a U.S.-based missile defense system in Europe. And he wants NATO to expand its borders. At the center of the trip is the NATO summit, starting Wednesday in Bucharest, Romania. The war in Afghanistan is under fresh review as the 26-nation NATO alliance confronts al-Qaida and Taliban forces, rising violence and internal debate about whether countries are contributing enough.