Meanwhile, 4,000 U.S. troops backed by aircraft, intelligence units and Iraqi forces were scouring the farming area around Mahmoudiya and the nearby town of Youssifiyah for the third day, as the military promised to make every effort available to find the missing soldiers. Lt. Col. Christopher Garver, a U.S. military spokesman in Baghdad, said the military could not verify the claim by the Islamic State of Iraq but "it would not surprise me if ... al-Qaida in Iraq is involved in this because there are similarities to what they've done before." He pointed out that the terror network also had claimed responsibility for killing two U.S. soldiers whose mutilated bodies were found after they went missing in the same area last year. The Islamic State in Iraq offered no proof for its claim on Internet that it was behind the attack Saturday in Mahmoudiya, about 20 miles south of Baghdad, that also killed four U.S. soldiers and an Iraqi translator.