NEW YORK (AP) — A Kenyan man was convicted Monday of plotting an attack 9/11 style attack in an American building on behalf of the terrorist organization al-Shabab.

A federal jury in Manhattan found Cholo Abdi Abdullah guilty of all six charges he faced for conspiring to hijack a plane and crashing it into a building, according to court records.

He is due to be sentenced next March and faces a mandatory minimum of 20 years in prison.

Abdullah represented himself during the trial, which began last week. He refused to give an opening statement and did not actively participate in the questioning of witnesses.

In court papers filed before the trial, prosecutors said Abdullah intended to “simply sit passively through the trial, not oppose the prosecution and whatever the outcome was, he would accept it because he does not believe this is a legitimate system.”

Lawyers appointed to assist Abdullah in his self-defense did not respond to an email seeking comment on Monday.

Federal prosecutors, who concluded their case Thursday, said Abdullah planned the attack for four years and received extensive training in explosives and how to operate secretly and avoid detection.

He then moved to the Philippines in 2017, where he began training as a commercial pilot.

Abdullah had almost finished his two-year pilot training when he was arrested in 2019 on local charges.

The following year he was transferred to US law enforcement authorities, who charged him with terrorism-related crimes.

Prosecutors said Abdullah also researched breaking into a cabin door and information “about the tallest building in a major American city” before he was caught.

In 2008, the State Department designated Al Shabab, which means “the youth” in Arabic, as a foreign terrorist organization. The militant group is an affiliate of Al Qaeda that has fought to establish an Islamic state in Somalia based on Shariah law.