Washington ? Five years before the worst terror attack in American history, a U.S.-educated Kuwaiti pitched an outlandish idea to Osama bin Laden.

Khalid Shaikh Mohammed, now a U.S. captive, concedes his apocalyptic vision of 10 planes steered into nuclear power plants, skyscrapers and other American targets received only a lukewarm response from the al-Qaida kingpin.

The meeting in Afghanistan in mid-1996, however, apparently was the genesis of the attacks that killed nearly 3,000 people on Sept. 11, 2001. Three reports issued this week by the Sept. 11 commission provide the fullest picture yet of how Mohammed’s idea evolved from wild scheme to unfathomable reality — and the government’s chaotic response.

New plan

Mohammed had targeted U.S. airliners before. He was indicted in the United States earlier in 1996 for plotting to bomb 12 flights over the Pacific Ocean, but he wasn’t captured. Mohammed, born in Kuwait and a 1986 graduate of North Carolina Agricultural and Technical State University, also wanted to crash a plane into CIA headquarters.

His new plan needed bin Laden’s money and his muscle.

Between May 1996, when bin Laden moved to Afghanistan from Sudan, and the Sept. 11 attacks, more than 20,000 men trained at his terror camps. They learned to be soldiers and, the Sept. 11 commission said, “to think creatively about ways to commit mass murder.”

They floated ideas: take over a Russian launch site and fire a nuclear missile at the United States, pump poison gas into a building’s air conditioning, hijack a plane to attack a city.

Who, what, where

Advanced terrorism training was given to only the most promising recruits, among them the Sept. 11 hijackers. Early in 1999, bin Laden gave the go-ahead for a scaled-down version of Mohammed’s proposal three years earlier.

According to Mohammed, the two drew up a list of potential targets:

l The Capitol, perceived source of U.S. policy in support of Israel.

l The White House and Pentagon, both advocated by bin Laden as potent American symbols.

l The World Trade Center, favored by Mohammed, whose nephew Yousef was in prison for the 1993 bombing of the towers that represented America’s financial might.

Bin Laden selected potential suicide hijackers. The first two arrived in Los Angeles on Jan. 15, 2000. During the next 18 months, 17 more followed, some entering the country on fraudulent visas. Four, including ringleader Mohammed Atta, attended U.S. flight schools.

FBI agents in Arizona and Minnesota were suspicious of the flight students, but their alarms went unheeded by higher-ups.

The summer of 2001 was a time of intensive preparation by the hijackers. They rode cross-country flights for surveillance, brought boxcutters onto planes as tests, practiced flying rented planes and honed their strength at gyms.

Meanwhile, in Afghanistan, senior al-Qaida leaders were under pressure from the Taliban not to attack inside America’s borders. Some feared U.S. military retaliation. Despite the pressure, bin Laden prodded Atta to get on with it.

Final preparations

In mid-August, Atta settled on the date of Sept. 11, choosing a week when Congress would be back from summer break. Bin Laden wanted to strike the White House; Atta preferred the Capitol as an easier target. The commission said it had been unable to determine definitely which was the intended target on Sept. 11.

The hijackers bought their flight tickets in late August and early September. Then, ever loyal, they took care of a final detail — sending back to al-Qaida $36,000 they didn’t need.

At the airports early on Sept. 11, nine of the hijackers were pulled aside for extra security screenings, but all were allowed to proceed, some with hidden knives and boxcutters.

At 8 a.m., American Airlines Flight 11 took off from Boston, with five hijackers aboard. Within 45 minutes, the other 14 hijackers were airborne: on flights out of Boston at 8:14, from Dulles airport near Washington at 8:20, from Newark, N.J., at 8:42.