The B-52 was filmed by a Vietnam culture-ministry official, a recent defector to the United States, who says his film is in Hanoi’s archives. But it was a large cache of 4,800 photos of American prisoners and soldiers killed in action discovered in a Hanoi war museum by U.S. historian Tim Schweitzer and smuggled out last summer, that helped Washington play hardball diplomacy with Hanoi. U.S. officials confronted Vietnamese Foreign Minister Nguyen Manh Cam with the evidence that Hanoi had, in fact, systematically kept track of the fate of Americans. On a follow-up trip to Hanoi by the special U.S. emissary on POW-MIA affairs, retired Gen. John Vessey, and Arizona Sen. John McCain, a former POW, Vietnamese officials agreed to open the POW archives.

Bush warned last week that he would not normalize diplomatic relations with Hanoi or lift the economic embargo until Vietnam has delivered a “full accounting” on all American personnel. The inquiry could take months, if not years, to complete. U.S. officials must proceed gingerly because Vietnamese hard-liners, who believe they have secrets to hide may try to end the unprecedented cooperation between the two old enemies.