Nearly two decades after the North Vietnamese shot down his Navy plane and held him captive for 5 1/2 years, John McCain is returning to Hanoi seeking an accounting of nearly 2,300 Americans still officially listed as missing in Southeast Asia.

His trip, as guest of the communist government, is not the first visit to Vietnam for the Republican senator from Arizona since his release from a prisoner of war camp. He toured Hanoi and Saigon in 1985 during the 10th anniversary of the fall of Saigon, and even visited his old cell -- with a request that the door not be closed behind him.

The current visit is to press Vietnamese officials about the fate of the Americans listed as missing, possible emigration of Amerasian children, the chance for peace in Cambodia and the release of political prisoners.

McCain, who left Washington over the weekend, is to fly from Bangkok to Hanoi Wednesday for a two-day stay and then go to Ho Chi Minh City, formerly Saigon. He also will visit the Cambodian capital of Phnom Penh and Laos.

The senator, a member of the Armed Services Committee, will be accompanied by officials from the National League of POW-MIA Families and the Vietnam Veterans of America.

The U.S. government lists 2,288 Americans as missing in action since U.S. forces withdrew from Southeast Asia, though it contends there is no evidence there are American prisoners still held in the region.