Taliban leaders have pulled off a stunning jailbreak in Afghanistan, freeing nearly 500 prisoners on Monday without firing a single shot. The "audacious plot" reportedly took months to prepare. Here, a brief guide to how they did it, and what the security breach means for the war effort:

How did the prisoners break out?
Well, technically, they didn't. Their comrades on the outside broke in. Taliban militants rented a house within shooting distance of the guard towers at Kandahar's Sarposa prison — the largest in southern Afghanistan. Over five months, 18 men dug a tunnel that went directly to the wing housing political prisoners and captured Taliban fighters.

That must have been some tunnel, right?
Indeed. The tunnel was about three feet in diameter, with battery-powered lights, air pipes, and small fans for ventilation. It stretched nearly 1,200 feet, starting in a mud-walled compound, running under a highway, passing about seven feet beneath security posts and the prison's tall concrete walls, and emerging in a prison cell. In some spots — especially where the busy road passed overhead — the tunnel had sturdy steel supports to prevent a cave-in. A Taliban spokesman told BBC News that trained engineers made sure the militants did everything right. "We had proper digging equipment," he said. "There was so much earth from the tunnel that we carried it away gradually and sold it in the market."

Didn't the guards know something was up?
Not until it was too late. Only a few people inside the prison knew about the plan in advance. The rest of the escapees only found out when they were woken up room by room, and led out in small groups. The leaders reportedly used copies of keys provided by "friends" of the Taliban to open the cells. One escapee told The New York Times — by telephone from near the Pakistan border — that he knew nothing until a cellmate tugged on his sleeve to wake him up. Another escapee told Britain's Telegraph that the guards were clueless. "They are always intoxicated, smoking heroin, smoking hashish, or sleeping," he said, as quoted by the Telegraph.

How long did the escape take?
It took more than four hours to get the 476 prisoners out, and the prison alarm didn't go off until a half hour after the last escapee left around 3:30 a.m. Monday. By then, the escapees had been shuttled to safe houses; only a few dozen were recaptured. According to Taliban sources, 106 of the men who escaped were Taliban commanders, and four were former provincial chiefs.

How badly will this set back the fight against the Taliban?
A spokesman for Afghanistan's president, Hamid Karzai, called the jailbreak a "disaster." The last massive escape occurred three years ago — when suicide bombers blasted open Sarposa's gates and 900 prisoners escaped — and was followed by a spike in Taliban attacks in Kandahar province. Government officials fear this time will be no different. "The Taliban gain two things from this jailbreak," says Muhammad Naiem Lalay Hamidzai, a Parliament member from Kandahar, and chairman of the internal security committee, as quoted by The New York Times. "It sends a message that they can do whatever they want, even at the heart of the most secure and important jail, and it allows them to strengthen their ranks with more manpower."

Sources: NY Times, Telegraph, BBC News, Wired