VIENNA Iran 's supreme leader has rejected direct negotiations with the United States over his country's nuclear program, likely slamming the door shut on a last-ditch effort to halt the reimposition of United Nations sanctions on Tehran. Ayatollah Ali Khamenei's remarks, aired on Iranian state television on Sept. 23, likely constrain any possible outreach to the U.S. by Iranian President Masoud Pezeshkian, who is in New York for the U.N. General Assembly. Separately, Iranian Foreign Minister