Washington ? U.S. special operations troops combing Iraq for Scud missiles and chemical or biological weapons have found none so far, a senior American military officer said Saturday.

Maj. Gen. Stanley McChrystal, the vice director of operations for the Joint Chiefs of Staff, said at a Pentagon news conference that the Iraqis had not fired any Scuds and that U.S. forces searching airfields in the far western desert of Iraq had uncovered no missiles or launchers.

Iraq denies having any Scuds, which have sufficient range to reach Israel, but Gen. Tommy Franks, who is running the war, said Saturday that Iraq had yet to account for about two dozen Scuds that U.N. inspectors have said were left from the 1991 Gulf War.

Iraq also denies it holds any chemical or biological weapons. McChrystal said the United States would either bomb any such weapons it should find or seize them with ground forces, whichever is safer. He and other officials refused to say where in Iraq those searches are happening.

Also Saturday, the U.S. military abandoned plans to open a northern front against Iraq that would have sent heavy armored forces streaming across the Turkish border.

Two U.S. defense officials said dozens of U.S. ships carrying weaponry for the Army’s 4th Infantry Division would head to the Persian Gulf after weeks of waiting off Turkey’s coast while the two countries tried to reach a deal.

McChrystal said that even without the 4th Infantry, “there will be a northern option.” He would not say what that might be. Other officials said Army airborne troops might join small numbers of U.S. special operations forces already on the ground in northern Iraq, where American officials fear clashes between Turkish forces and Iraqi Kurds.

A British Royal Air Force GR7 Harrier is waved on by ground crew as it taxis to the runway on their base in Kuwait prior to a mission over Iraq. U.S. and British forces besieged the southern city of Basra on Saturday and pounded Baghdad in the first daylight air raids of the war.

Although U.S. officials on Friday said all 8,000 soldiers in Iraq’s 51st Mechanized Division in southern Iraq has surrendered, McChrystal said Saturday that only the unit’s commanders gave themselves up. The rest simply left the battlefield or were “melting away,” he said.

McChrystal said the number of Iraqi prisoners of war was between 1,000 and 2,000.

In describing overall progress in the war, McChrystal said American and British forces had hit Iraq with 500 cruise missiles — 400 launched from ships and submarines and 100 launched from Air Force bombers — and several hundred precision-guided bombs over the past day. The use of air-launched cruise missiles in Friday’s attacks was the first since the war began.

Warplanes flew 1,000 missions from aircraft carriers and air bases in the region, he said.