Washington ? It’s only 300 miles to Baghdad for U.S. and British tanks arrayed on Iraq’s border.

How fast they can cover the distance depends on the “speed bumps” they encounter, military slang for obstacles big and small, such as Iraqi resistance, a chemical attack and logistical problems of the Pentagon’s own making.

“I think they’re going to put the pedal to the metal and take about a 300-mile drive through the desert … then turn right when they get to Baghdad,” said John Pike, military analyst with GlobalSecurity.org, a consulting company.

In the threatened war to disarm and overthrow President Saddam Hussein, expectations are that the main ground force could reach Baghdad in as few as two days to four days.

Fast and ferocious is the goal of some 230,000 air, sea and land forces amassed in the Persian Gulf region, including 145,000 just over Iraq’s border in Kuwait, some 300 miles from Baghdad, the capital. There also are some 45,000 British forces in the region.

If President Bush orders war, the campaign would include a massive barrage of bombs and missiles over a wide range of Iraq at once.

Near simultaneous ground assaults by armored units would move from the south. Lighter airborne troops would drop into locations to seize and secure oil wells, missile launch sites and suspected chemical-biological weapons sites, according to parts of the war plan widely leaked to the press.

The idea is to overwhelm Iraqi forces — the Defense Department says “shock and awe” them — in the hope they will abandon or turn on Saddam.

A planned ground assault in the north from Turkey is being reworked because the United States did not get approval to base troops there.

In the south, British forces and U.S. Marines have plans to make one thrust from Kuwait toward the northeast, either taking or going around the city of Basra, officials have said. But the main drive, led by the Army’s 20,000-strong 3rd Infantry Division, would push off to the west of the British operation, they said.

Armored columns of tens of thousands of troops, tanks and trucks would go over the border, supported by airborne units that can leapfrog ahead, then drop down to seize critical areas, establish forward bases and eliminate obstacles in the path of ground forces, officials said.

That includes Abrams tanks, Bradley Fighting vehicles, scout vehicles, mobile command centers, mobile bridges for crossing small rivers and a logistics tail of food, ammunition, fuel, spare parts and other supplies.

The trip alone for the huge, heavy force would take some 18 hours, military analysts said.

“That’s if absolutely everything thing went well, it was totally uncontested,” said Robert Work of the Center for Strategic and Budgetary Assessments.