Walli Mujahidh, 34, pleaded guilty in December 2011 to charges of conspiracy to kill officers of the United States, conspiracy to use weapons of mass destruction and unlawful possession of a firearm,according to the Seattle Times.
"I would like to apologize to my country for my betrayal," Mujahidh wrote in a letter that was read to the court this morning. "I would like to apologize to my religion. My actions were cowardly and shameful. I accept full responsibility."
Federal prosecutors said Mujahidh and co-conspirator Abu Khalid Abdul-Latif plotted to use grenades and machine guns to kill American military recruits at Seattle's Military Entrance Processing Station.
According to the FBI, the pair hoped to become martyrs and inspire like-minded radical Muslims to attack their fellow Americans. The attack was planned in revenge for what they saw as the innocent killing of Muslims oversees by the US military.
"This would have been a devastating attack with a toll of 150 victims," said assistant United States Attorney Todd Greenberg in court this morning.
The FBI and Seattle police tracked Mujahidh and Abdul-Latif using a paid police informant who secretly recorded their conversations.
Mujahidh originally agreed to spend 27 years behind bars as part of his plea deal but that agreement was struck down after it came to light that the confidential informant had erased hundreds of text messages between him and his police handler.
The defense claimed those erased messages could have helped their client's case, reports KING 5 News.
Abdul-Latif, 35, was sentenced to 18 years in prison last month followed by ten years of supervised release.
Abdul-Latif previously pleaded guilty to conspiracy to kill US officers and conspiracy to use weapons of mass destruction.