The four served in the U.S. Air Force, the department said in a news release. Two were identified as Maj. Barclay B. Young of Hartford, Conn., and Senior Master Sgt. James K. Caniford of Brunswick, Md. Families of the other two men asked that their names not be released.

The department said the men were among 14 aboard an AC-130A Spectre gunship flying an armed reconnaissance mission over southern Laos in March 1972. The aircraft was struck by an enemy surface-to-air missile and crashed. Search and rescue efforts were stopped after a few days because of heavy enemy activity in the area.

In 1986, a joint U.S.-Lao People's Democratic Republic team found human remains and other items when they surveyed and excavated the crash site in Laos' Savannakhet province, the department said. During the next several years, other excavations led to the recovery of more human remains and other items.

The crewmen were identified using forensic identification tools, circumstantial evidence, and DNA and dental comparisons.