On May 12, 1975, the S.S. Mayaguez, an American merchant ship, was seized in international waters off the Cambodian coast by the Cambodian Navy. President Gerald Ford ordered U.S. Naval forces to the Gulf of Thailand and set in motion a rescue operation. On May 15, Marines flown by helicopters of the 3rd Aerospace Rescue and Recovery Group and the 21st Special Operations Squadron began the rescue. Eighteen Marines and Airmen were killed or missing in the assault, as well as twenty-three others killed in a helicopter crash en route. The objectives of the mission were achieved. The Mayaguez and its crew had been rescued, though at a high cost.