US President George W. Bush on Saturday swatted down calls in Congress for a US troop withdrawal from Iraq, saying that American military leaders believe that retreat now would be "a recipe for disaster." Bush defended his Iraq strategy in remarks prepared for a speech at Osan Air Base, headquarters for the 7th Air Force, the primary US Air Force unit in South Korea. Traveling in Asia, there has been no respite from Iraq for Bush. He's had to deal with an Iraq rebuff from a friend, South Korea, and with turmoil over his policies back home. "In Washington there are some who say that the sacrifice is too great, and they urged us to set a date for withdrawal before we have completed our mission," the president said. "Those who are in the fight know better." Back home, Rep. John Murtha, a prominent Democrat defense hawk, called for a US withdrawal from Iraq over six months. In a speech Thursday, Murtha said, "Our troops have become the primary target of the insurgency. They are united against US forces and we have become a catalyst for violence. The war in Iraq is not going as advertised. It is a flawed policy wrapped in illusion."