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Nearly a quarter-million U.S. soldiers are within weeks of passing through this desert kingdom on their way to or from the war in neighboring Iraq (search), the largest such rotation of American forces in history, according to military planners overseeing the project.

"This is a breathtaking, history-making operation," said Army Maj. Gen. Stephen M. Speakes, who runs the rotation from this sand-blown base south of Kuwait City (search).

Explaining the troop rotation is simple: About 130,000 U.S. soldiers in Iraq will go home and 110,000 will take their places for about a year, in Operation Iraqi Freedom 2.

Getting it done is another matter.

The maneuver involves eight of America's 10 active Army divisions and a U.S. Marine Expeditionary Force (search), along with 40,000 troops from a few dozen countries in the U.S.-led coalition.

Military planners have choreographed the arrivals of dozens of ships and hundreds of aircraft bearing fresh troops and their gear into Kuwait, the center of the operation. The new arrivals swap places with weary soldiers streaming in from Iraq on trucks and planes that, in a matter of hours, turn around and ferry newcomers north.

Already, as many as 4,000 trucks are on the road between Kuwait and Iraq at any moment, said Army Brig. Gen. Jack Stoltz, who directs movement of troops and distribution of equipment.

That number will rise as the rotation hits a crescendo in early March, when as many as 60,000 troops at a time will be passing through Kuwait, ferrying enormous amounts of gear, including tanks, Bradley Fighting Vehicles and helicopters.

By the time the rotation finishes in May, the Pentagon will have shipped nearly 450,000 tons of equipment to the Iraqi theater and sent home even more -- 700,000 tons.

"It's like a ballet, except it's the Green Bay Packers that are dancing," Stoltz said in a meeting with The Associated Press. "Logistics is brute force."

The Army has engineered the rotation so that battle-numbed U.S. forces rarely meet their fresh replacements, even though both groups pass through Kuwait at the same time. Homebound troops stay at camps close to the seaports. New arrivals are trucked to desert camps where they assemble their gear and train to kill the rebels who may attack their convoy when it crosses the Iraqi border.

After March, from the point of view of U.S. military's transportation gurus, the U.S. operation in Iraq will wind down, demanding fewer ships, planes and trucks.

In the fall, the rotation for Operation Iraqi Freedom 3 will creak to life, and Speakes and his subordinates will start over. That maneuver will send around 100,000 or so U.S. troops into Iraq, but with fewer vehicles and supplies. Many are expected to be the same troops now heading home.

"This is a nonstop cycling business we're in," Speakes said. "As soon as we finish this one, we'll be planning for the next."

Speakes and his staff aren't just developing the troop rotation for use in the Iraq. The sweeping operation is also being modeled for moving U.S. soldiers in future wars, Speakes said.

The surging operation has left Kuwait awash in the American military, despite U.S. efforts to keep a low profile.

People strolling along Kuwait City's seaside Corniche watch Navy cargo ships steaming in and the Air Force's fat gray C-17 Globemasters lowering their wheels over the city. Gritty Army convoys that stretch to the horizon roll south on the kingdom's coastal highway, and clean ones sweep past in the other direction.

Kuwait's ruling sheiks, still grateful to the United States for driving out Iraq's invading army in 1991, have given the Americans broad swaths of the desert kingdom in which to house troops, store vehicles, land planes, berth ships, assemble convoys and fire weapons.

The U.S. military has 14 camps and bases in Kuwait, including a pair of seaports, a pair of airports and a choice piece of coastal real estate.

At Camp Arifjan, a sprawling series of yards have been set up for convoys arriving from Iraq.

Drivers pull up to bins and deposit ammunition, spare parts the rest of the vehicle's contents. Then slicker-wearing teams of soldiers blast away a year's worth of Iraqi grime with a hard spray, disinfecting every truck, armored vehicle or Humvee going back to the United States or Europe.

A building nearby houses the nerve center of the rotation: a multimedia theater resembling a university lecture hall, called the command operations intelligence center. There, officers control the troop flows, checking weather, watching the progress of convoys inching across a map of Iraq and informing drivers of insurgent zones in Iraq.

"If there's a threat out there, we will reroute," said Army Col. Billy Pratt, who runs the center.

Synchronization is crucial to prevent bottlenecks, Pratt said.

There is bed space for just 60,000 soldiers in Kuwait, so the commanders need to get the soldiers in and out within about two weeks to free up space for the next batch. The delay of one aircraft or ship -- or it arriving too early -- can muck up the entire plan, since newcomers and homebound troops travel aboard the same trucks, planes and ships.

For the past 46 days, the plan has worked. Every truck hauling people or gear into Iraq has returned with cargo going home, Speakes said.

The mark of final success, said Speakes, is to move the 250,000 troops and their gear without reducing the firepower available to the top U.S. commander in Iraq, Lt. Gen. Ricardo Sanchez.

"We want him to say he never noticed it," Speakes said.