A former shuttle driver at Denver's airport, Najibullah Zazi, pleaded guilty Monday to conspiring with others to bomb the New York City subway system on September 2009.

Zazi admitted to conspiring to use weapons of mass destruction, conspiracy to commit murder outside the U.S. and providing material support to al Qaeda before U.S. District Judge Raymond Dearie in Brooklyn.

The plan was to conduct a martyrdom operation on the New York subway lines, Zazi told Judge Dearie, Bloomberg noted.

I would sacrifice myself to bring attention to what the U.S. military was doing against civilians in Afghanistan, Mr. Zazi said, according to the Associated Press.

Zazi, an Afghan native who once lived in New York City, faces a sentence of life in prison.

He said he went to Pakistan in 2008 to join the Taliban and fight against the U.S. but that he was recruited by terrorists and went into a training camp, the Associated Press reports.