A former U.S. Marine accused of planning a Christmas holiday terrorist attack on San Francisco's iconic Pier 39 in 2017 before he was foiled by the FBI was sentenced on Monday to 15 years in prison.

Everitt Aaron Jameson, a California 27-year-old who pleaded guilty in June to attempting to provide material support to the Islamic State, also faces a life term of supervised release, according to a Justice Department news release regarding U.S. District Judge Lawrence O'Neill's decision.

Jameson first came to the notice of the FBI in September and later told a confidential source he was wholeheartedly committed to the Islamic State's cause while voicing his appreciation of the Oct. 31 terrorist attack in New York City, among other such incidents.

He then met two undercover FBI agents posing as Islamic State figures and offered to donate money and commit violent acts on the organization's behalf. In addition, he touted how his military training had prepared him for combat and war, as well as extolling his knowledge of the Anarchist Cookbook, which details how to make explosives.

Jameson served with the Marines in 2009 and gained a sharpshooter rifle qualification before he was discharged for fraudulent enlistment after it was discovered he failed to disclose his asthma history.