BAGHDAD — U.S. bombers and jet fighters unleashed 40,000 pounds of explosives during a 10-minute airstrike Thursday, flattening what the military called safe havens for Al Qaeda in Iraq on the southern outskirts of the capital.The strikes, carried out above approaching U.S. and Iraqi troops, was part of Operation Phantom Phoenix, a nationwide campaign launched Tuesday against Al Qaeda in Iraq.The air raid was followed by a ground attack that led to 12 arrests and the discovery of two houses used to torture kidnap victims, according to an Iraqi army officer who spoke on condition of anonymity because he was not...