President George W. Bush on Thursday rejected critics of the Iraq war who demand a U.S. pullout and cast the conflict as necessary to prevent Islamic militants from gaining a foothold for a sweeping empire. "We will never back down, never give in and never accept anything less than complete victory," Bush said in a speech on Washington's war on terrorism. Bush used new and more specific language in characterizing the opponents as part of an Islamic radical movement "with a clear and coherent ideology" and territorial ambitions, rather than dismissing them as the terrorist "evildoers" of his early speeches...