HANOI, Vietnam (AP) — Remains believed to be those of four American airmen killed during the Vietnam War were placed on a U.S. military transport plane in Hanoi on Tuesday and sent back to the United States to be identified.

The four aluminum cases holding the remains were draped with American flags as uniformed U.S. soldiers carried them onto the plane at Noi Bai International Airport. The remains were headed to Hawaii for forensic testing.

The repatriation was the 108th, according to the MIA office in Hanoi.

The remains were recovered from four different sites in northern Vietnam in the past two months, said Lieutenant Col. Todd Emoto of the MIA office.

"It is a very good percentage," Emoto said. "We found four sets from four sites. The cooperation with our Vietnamese counterpart is exceptional."

The remains are believed to be those of airmen because they were found in northern Vietnamese provinces where U.S. ground forces were not active during the conflict.

The MIA office said there was some additional evidence indicating they were airmen but did not give specifics.

More than 2,600 U.S. servicemen sent to Southeast Asia during the Vietnam War were unaccounted for when the conflict ended in 1975 with a victory by northern communist forces, who seized control of U.S.-backed South Vietnam and unified the country. Some 1,348 American soldiers remain unaccounted for.

An estimated 58,000 Americans and 3 million Vietnamese were killed in the war.