Vienna, Austria ? The U.N. atomic agency told Iran Friday to prove by the end of October that its nuclear aims are peaceful, issuing a tough resolution that Tehran’s chief delegate condemned as reflecting Washington’s appetite for “confrontation and war.”

Iranian chief delegate Ali Akbar Salehi walked out of the meeting to protest the deadline — and the prospect of U.N. Security Council involvement — contained in a U.S.-backed resolution to a meeting of the International Atomic Energy Agency.

“We reject the ultimatum in this draft,” Salehi said, calling it a “disaster for the agency.”

If the agency rules at its next meeting in November that Iran did not meet demands in the resolution, it could rule Tehran in noncompliance of a part of the Nuclear Nonproliferation Treaty banning the spread of nuclear weapons.

The agency is obligated to report noncompliance to the Security Council, whose range of action reaches from criticism to economic sanctions.