A Northern Virginia man on Monday was sentenced to 23 years in prison for his role in a plot to carry out terrorist bombings at stations in the Washington Metro system.

Farooque Ahmed, 35, who was arrested last fall in an undercover sting, pleaded guilty to two terrorism related charges in U.S. District Court in Alexandria. Federal authorities said Ahmed conspired with people he thought were al-Qaeda operatives to bomb the Arlington Cemetery, Pentagon City, Crystal City and Court House stations.

“I cannot describe in words... all I can say is I’m sorry,” Ahmed said in court. “It was the wrong action.”

According to court papers, Ahmed met with with federal agents who posed as Islamic radicals. During meetings held at Northern Virginia hotels, he agreed to conduct video surveillance of the stations and suggested the best time to attack and the best location to place explosives to harm passengers.

Ahmed pleaded guilty to attempting to provide material support to a designated foreign terrorist organization and collecting information to assist in planning a terrorist attack on a transit facility.