NEW YORK -- "He's never really been shy I guess, about stating what he believes," said attorney Arthur Folsom when asked to describe his former client, Najibullah Zazi.

Zazi, formerly of Aurora, has pleaded guilty to federal charges involving a terrorist plot to bomb the New York City subway system.

"I think in his mind he was doing that which was on course with what he believed," said Folsom.

In his plea deal with the federal government, Zazi indicated he was angry about the U.S. military action in Afghanistan.

Folsom told 7NEWS that Zazi wanted to bring attention to the deaths of Afghan civilians in the conflict.

"Did you expect him to enter these kinds of guilty pleas?" asked CALL7 Investigator Tony Kovaleski.

"I expected there was going to be some kind of guilty plea involved. I never thought this was going to go to trial," said Folsom.

Zazi said he went to Pakistan in 2008 to join the Taliban and fight against the U.S. military but was recruited by the terrorist network and went into a training camp.

He admitted building homemade explosives with beauty supplies purchased in the Denver suburbs and cooked up in a Colorado hotel room, then driving them cross-country to New York City just before the eighth anniversary of the Sept. 11 terror attacks.

Zazi told authorities he disposed of the explosives once arriving in New York.

He said the terrorism plot was aimed at the city subway system but wouldn't name a specific target when asked by U.S. District Judge Raymond Dearie.

Zazi was arrested in the fall after arousing authorities' suspicions by driving cross-country from Denver to New York around the anniversary of the Sept. 11, 2001, attacks.