The U.S. Army's heaviest ground firepower reached Saudi soil today for deployment behind Arab forces manning the front line in the monthlong standoff with Iraq. Dozens of M1-1P tanks and M2 Bradley armored infantry fighting vehicles, and scores more heavy support vehicles, rolled off two huge transport ships at a port in northeastern Saudi Arabia and were readied for the trip north into the desert. The M1s are by the far the biggest ground weapon in the burgeoning U.S. arsenal in Saudi Arabia, weighing an imposing 60 tons and carrying a 105 mm cannon said to be accurate at 6,600 feet or more. The huge but speedy tanks _ which can travel about 45 mph _ left the 24th Infantry (Mechanized) Division's home in Georgia two weeks ago. The 24th's heavy firepower will be deployed in front of most other U.S ground forces in Saudi Arabia but still a good distance behind the Saudi-led Arab forces, which are just miles from the border with occupied Kuwait. The U.S. buildup _ which could reach 200,000-250,000 ground forces _ is not expected to be completed until October. Transport planes are arriving around the clock, but the M1s and the 24th's other heavy weaponry have been long awaited by U.S. military commanders. Until now, the U.S.-led multinational Saudi defense force has been short on heavy ground firepower. ``This is boss,'' Sgt. Ronald Ruff said as he showed off his M1 to a group of reporters. ``This is the Cadillac model. This is the top of the line.'' Up to now, the only U.S. tanks in Saudi Arabia have been Vietnam era M60s, brought by the 7th Marine Expeditionary Brigade, and even smaller M551 Sheridans. Iraq has a formidable force of Soviet-made tanks, primarily the export versions of its T64 and T72 models. The T64 is comparable in armament and armor to the M1s that arrived today; the T72 is equivalent to the more modern M1, the M1-A1. The U.S. tanks are considered to have superior weapons sighting and guidance systems, and the strategy for any tank war with Iraq is to use the air superiority of the American, Saudi and British forces to inflict heavy early damage on Iraqi tanks. ``There's no doubt in my mind that we'll succeed here if we have to,'' said Lt. Col. Barry Willey. ``Bring them (the Iraqis) on,'' Ruff said. ``We've the training and technology; they've got the numbers. We'll take them out.'' Several M1 crews said they will have to clean and change the M1's filters more often because of the talcum-like sand of the Saudi desert.