(Updates with Bush quotes, new throughout) By Caren Bohan WASHINGTON, Dec 20 (Reuters) - Iraqi insurgents have thwarted U.S. efforts to establish security, President George W. Bush said on Wednesday, and he pledged that any boost in American troops would be tied to a specific mission to curb violence. Bush, who is rethinking his war strategy, spoke of setbacks this year but predicted victory and insisted the United States would neither abandon Iraq nor be driven from the region. "They can't run us out of the Middle East," he said at a news conference. "They can't intimidate America." Bush said provocative attacks such as the February bombing of a holy Shi'ite shrine were part of a strategy by insurgents to foment sectarian strife. "And over the course of the year they had success," Bush said. "Their success hurt our efforts to help the Iraqis rebuild their country. They set back reconciliation and kept Iraq's unity government and our coalition from establishing security and stability throughout the country." Bush plans to roll out a fresh plan for Iraq in January. He said one option under review was a short-term increase in U.S. troop levels there. He also endorsed a longer-term increase in the overall size of the U.S. military, a change previously resisted by his administration. Some White House officials are said to be pushing for a "surge" of tens of thousands of troops in Iraq to try to calm violence to give the Iraqi government time to work on political reconciliation and allow the Iraqi army to get up to speed. But some in the military are skeptical that more U.S. troops in Iraq are the answer. Gen. John Abizaid, the U.S. military commander of forces in the Middle East who will retire early next year, said last month that "troop levels need to stay where they are," rejecting calls for increases or withdrawals Bush said he would only support a troop increase if the there was a "specific mission that can be accomplished." In a Washington Post interview on Tuesday, Bush had said of Iraq, "We're not winning, we're not losing." That was a reversal from his insistence in the weeks before November's U.S. congressional elections that the United States was "absolutely" winning in Iraq. Asked to explain his apparent change of heart, Bush said his comment "reflected the fact that we're not succeeding nearly as fast as I wanted, when I said it at the time, and that the conditions are tough in Iraq, particularly in Baghdad." He conceded Americans were troubled by "unspeakable" violence in Iraq but said he believed the public supported his view that an immediate U.S. pullout was not the right course. Bush has faced increased pressure to revamp his policy since last month's elections in which his Republican Party lost control of the U.S. Congress in elections last month, largely because of public discontent over the war. A new CNN poll shows most Americans are still hoping for a dramatic shift. Almost three-quarters in the survey, taken Dec. 15-17, said they wanted a "complete overhaul" or "major changes" to the strategy. Twenty-four percent said they would be satisfied with minor adjustments or no changes. Bush's critics say his rhetoric, including his rejection of a timetable for a troop withdrawal, shows he is not heeding the electorate's message. Incoming U.S. House of Representatives Speaker Nancy Pelosi faulted Bush for not signaling that he is contemplating "the changes needed to reverse the disastrous situation in Iraq." But the California Democrat welcomed Bush's decision to back a permanent increase in the size of the military, and pointed out that many Democrats had pushed the idea. There are about 507,000 active duty U.S. Army soldiers and 180,000 Marines. Every additional 10,000 U.S. troops would cost about $1.2 billion a year in salaries and training, not including equipment, said Paul Boyce, an Army spokesman. (Additional reporting by Tabassum Zakaria)
