Three tough-as-nails Marines aboard a flight from Japan to Texas sprang into action and detained a fellow passenger who barricaded himself in the lavatory and began yelling threats, according to reports.

Capt. Daniel Kult, Sgt. John Dietrick and Pfc. Alexander Meinhardt — all with 1st Battalion, 6th Marines — were flying from Tokyo to Dallas/Fort Worth International Airport on Monday when the drama unfolded, according to Stars and Stripes.

Dietrick said that even though he was wearing headphones, he could hear that someone sounded “distraught,” CNN reported.

“We all heard the commotion and instinctively knew something needed to be done,” he told Stars and Stripes via text message. “The only thing that was going through our heads was to ensure the safety of all passengers on board and our fellow Marines.”

The three men gathered in a tactical “stack” at the toilet and prepared to subdue the passenger as a flight attendant unlocked the door.

“Honestly we just kind of naturally positioned ourselves in a manner to cover the exit and cover each other,” Kult, an infantry officer from Iowa, told the news outlet.

Using flex ties provided by the crew, the Marines restrained the unhinged passenger.

“You know how to work with a team, and you are trained to calmly insert yourself into a stressful situation,” Kult told Stars and Stripes. “Even though we are all different ranks, we’ve had shared experiences in training that made this an easy situation.”

After restraining the passenger in a seat, they guarded him for the rest of the flight, which was diverted to Los Angeles, where the man was taken to a hospital for a mental evaluation, according to the report.

The feds are investigating the incident.

The heroic trio was about halfway through a six-month deployment to Camp Schwab on Okinawa, but for different reasons, each was cleared to travel back to the US despite the Defense Department’s coronavirus-related stop movement order.

Their battalion commander, Lt. Col. Chris Niedziocha, said he knew all three of them and called them “men of action.”

“Honestly, I’m not surprised,” he said of their actions.