Iran is serious about its program of enriching uranium but will cooperate with the U.N. nuclear watchdog and avoid adventurism, Iran's supreme leader Ayatollah Ali Khamenei told the visiting Russian president. Khamenei made the comments during a meeting late Tuesday with President Vladimir Putin who presented the Iranian leader a proposal to solve the international standoff over Iran's nuclear program. «We will ponder about your words and proposal,» the state news agency IRNA quoted Khamenei as saying about the offer. There are no official reports available on the contents of Putin's message.