Trial in France for Extremist Foiled by 3 Americans on Train

French President Francois Hollande bids farewell to U.S. Airman Spencer Stone, U.S. National Guardsman Alek Skarlatos (second from left), and Anthony Sadler (R), a senior at Sacramento State University in California, after Hollande awarded them the French Legion of Honor at the Elysee Palace, in Paris, on Aug. 24, 2015. Michel Euler/AP Photo

PARIS—An operative of the ISIS terrorist group went on trial on Monday in Paris on terror charges for swaggering bare-chested through a train in 2015 with an arsenal of weapons and shooting one passenger. He was brought down by three American vacationers in an electrifying capture that Clint Eastwood turned into a Hollywood thriller.

The scene five years ago on the fast train from Amsterdam to Paris is the focus of the month-long trial of Ayoub El Khazzani, with testimony expected from the two U.S. servicemen and their friend, who have been hailed as heroes.