WASHINGTON - (AP) - Looking beyond the wars he inherited, President Barack Obama on Thursday launched a reshaping and shrinking of the military. He vowed to preserve U.S. pre-eminence even as the Army and Marine Corps shed troops and the administration considers reducing its arsenal of nuclear weapons. The changes won't come without risk, Defense Secretary Leon Panetta said. But he called it acceptable and, because of budget restraints, inevitable. In a presentation at the Pentagon, Obama said the U.S. is "turning a page" after having killed Osama bin Laden, withdrawn troops from Iraq and begun to wind down the war in Afghanistan. He outlined a vision for the future that some Republican lawmakers quickly dubbed wrong-headed. "Our military will be leaner, but the world must know the United States is going to maintain our military superiority," Obama said with Panetta and the Joint Chiefs of Staff chairman, Gen. Martin Dempsey, at his side. In a presidential election year the strategy gives Obama a rhetorical tool to defend his Pentagon budget-cutting choices. Republican contenders for the White House already have attacked him on national security issues including missile defense, Iran and planned reductions in ground forces. Obama unveiled the results of an eight-month defense strategy review that is intended to guide decisions on cutting hundreds of billions from planned Pentagon spending over the coming decade. The eight-page document contained no details about how broad concepts for reshaping the military - such as focusing more on Asia and less on Europe - will translate into troop or weapons cuts. Those details will be included in the 2013 defense budget to be submitted to Congress next month.To watch Defense Secretary Leon Panetta discuss the looming military cuts, go to channel 612 on your iO digital cable box and select the 'iO Extra' tab.