Iran's supreme leader Khamenei Rejects U.S. Nuclear Proposal, Vows Iran Will Continue Uranium Enrichment. In a forceful speech on Wednesday, Iran’s Supreme Leader Ayatollah Ali Khamenei sharply criticized a new U.S. nuclear proposal, calling it “100 percent against” the principles of Iran’s 1979 Islamic revolution. Although Khamenei did not entirely close the door on a potential agreement with the United States, he was unequivocal in rejecting any deal that would force Iran to give up uranium enrichment a key component of the country’s nuclear program. The comments come amid the sixth round of indirect nuclear talks between Iran and the U.S., aimed at reviving a broader agreement and easing decades-long tensions.