United Nations ? In a scene reminiscent of Adlai Stevenson displaying aerial images of Soviet bases during the 1962 Cuban missile crisis, U.S. officials gave diplomats here a high-tech slide show Wednesday of satellite photos that they say prove Iraqis have illegally converted recently imported trucks to weapons carriers.

The unusual U.S. intelligence briefings were staged on the eve of the first high-level talks between Iraqi and U.N. officials in almost two years.

In a visit that diplomats say was prompted by U.S. threats of military action against his government, Iraqi Foreign Minister Naji Sabri is scheduled to meet today with U.N. Secretary-General Kofi Annan in New York before flying back to the Middle East for a round of consultations in Arab capitals.

Although Iraq requested the meeting, U.N. officials say Annan set the agenda: full Iraqi compliance with U.N. demands for the return of weapons inspectors, who left Baghdad hours before U.S. and British bombing raids there in December 1998.

“As far as the secretary-general is concerned, they will be talking about U.N. resolutions, and his emphasis will be implementation, implementation, implementation,” said Fred Eckhard, Annan’s spokesman.

The U.S. government says the spy photos it unveiled behind closed doors Wednesday document Iraq’s brazen violation of the U.N. resolution that established the so-called oil-for-food program, under which Iraq can import industrial goods such as heavy trucks only for “humanitarian” purposes.

Proof that Baghdad is systematically defying U.N. trade sanctions could effectively derail any Iraqi efforts to negotiate the removal of the import controls, even if Iraq unexpectedly shifts course and agrees to admit arms inspectors, diplomats here said.

And any evidence that Iraq is covertly rebuilding its army reinforces U.S. arguments that Saddam Hussein’s regime must be confronted militarily.

“It is doubly worrying,” said Catherine MacKenzie, an official at the British mission to the United Nations. “The military buildup that it would bring about adds to Iraq’s ability to project its power more effectively. And these are vehicles that should be distributing food and humanitarian supplies, a job that is not being done. We know that Iraq’s priority is weapons, not food or welfare, and this is one more graphic illustration of that.”