Why Abdulmutallab failed to blow up our plane – US

bomb attack in 2009 because the explosives he was wired with became 'degraded' after he wore the same pair of underpants for two weeks.

Abdulmutallab had, at the age of 23, confessed to and convicted of attempting to detonate plastic explosives hidden in his underwear while aboard a Northwest Airlines Flight 253, en route from Amsterdam to Michigan, US on December 25, 2009.

However, United States officials explained that the bomb failed to detonate aboard the flight, which was carrying nearly 300 people, but caused a brief fire that caused burns to his groin.

He was sentenced to life without parole in February 2012 after he pleaded guilty to all charges on the second day of his trial the previous October.

The U.S. Head of the Transportation Security Administration, John Pistole, said during the week that the bomb failed to detonate because of how long Abdulmutallab had been wearing his underwear.

Pistole said, "The bomber had had the device with him for over two weeks."

When he was then asked whether the bomb had become 'damp' Pistole replied that the explosive had become damp due to the length of days Abdulmutallab carried the device in his underwear.

During his trial, Abdulmutallab said the bomb in his underwear was a 'blessed weapon' to avenge poorly treated Muslims around the world.

However, after the bomb failed to detonate, passengers pounced on Abdulmutallab and forced him to the front of Northwest Airlines Flight 253 where he was held until the plane landed minutes later.