U.S. military experts, bolstered by promises of better Vietnamese cooperation, began their 12th joint search Wednesday for evidence of what happened to the 1,676 American servicemen missing in Vietnam, a U.S. embassy spokesman said.

"Two teams of U.S. technical experts have already arrived in Vietnam to work with their Vietnamese counterparts in an effort to resolve the fates of Americans missing or otherwise unaccounted for in Vietnam," said U.S. embassy spokesman James Williams.