President George W. Bush aims to inspire patience with the war in Iraq Tuesday by arguing that the fight against extremists there is crucial to US security and the future of a strategic, struggling region. Bush was to speak later Tuesday before thousands of veterans at the American Legion convention. It is his second major speech in a week devoted to an attempt to buttress support for the war. Last week before the Veterans of Foreign Wars convention, he likened today's fight against extremism in Iraq to past conflicts in Japan, Korea and Vietnam. On Tuesday, he plans to discuss the implications of the fight in Iraq for the broader Middle East, a global crossroads that has largely missed the democratic and economic advances seen in other parts of the world and is thus vulnerable to the rise of terrorism, said a senior administration official. The official spoke on condition of anonymity to avoid pre-empting the president.