A Seattle man was arrested on Friday, May 28, at Seattle-Tacoma International Airport on criminal charges related to his alleged efforts to join Islamic State of Iraq and al-Sham (ISIS), a designated foreign terrorist organization, in order to engage in violent acts of terrorism in the Middle East or the United States.

According to court documents, Elvin Hunter Bgorn Williams, 20, of Seattle, was arrested as he prepared to board an international flight following a lengthy investigation into his efforts to join ISIS.

“As alleged, Williams was determined to support ISIS either by traveling overseas to join and fight with the terrorist organization, or by conducting an attack here in the United States,” said Assistant Attorney General John C. Demers for the Justice Department’s National Security Division. “The FBI was just as determined to stop him, and he was intercepted as he tried to make his way abroad. The threat of terrorism at home and abroad remains, and the National Security Division is committed to holding accountable those who would provide material support to foreign terrorist organizations. I want to thank the agents, analysts, and prosecutors who are responsible for this case.”

Read more: Department of Justice