Nobel Peace Prize winner Mohamed ElBaradei said Monday he believes the United States will need to give Iran a security guarantee before a final agreement can be reached on the country's atomic program.

ElBaradei, who heads the International Atomic Energy Agency, also said the United States must become more involved in the stalled negotiations between Iran and the European Union aimed at making Tehran permanently freeze nuclear enrichment.

That process can produce material for use in warheads or fuel for nuclear plants to generate electricity.

"I think part of the negotiations should be providing Iran with security assurances," ElBaradei said.

Adam Ereli, a State Department spokesman, said Iran would get no guarantees without first acting "like a responsible member of the international community."

"But right now, I don't think people should be asking the United States, 'Why don't you do this or why don't you do that?"' Ereli said.

In September, North Korea agreed to abandon its nuclear program in exchange for security guarantees and energy aid, and ElBaradei said a similar package will be needed to reach a deal with Iran. Tehran temporarily froze its enrichment program in November 2004, but the Europeans want it permanently halted.

ElBaradei also said he the U.S. would take a stronger role in the talks, adding, "We look at the United States ... to do the heavy lifting in the area of security."

The United States backs the Iran-Europe talks, which broke off in August but will resume Dec. 21 in Vienna, Austria. Tehran since has restarted uranium conversion, a precursor to enrichment.

A senior State Department official said it was a matter of time before Washington reports Iran to the U.N. Security Council, where it could face economic sanctions for violating a nuclear arms control treaty.

"We're now talking 'when' or 'how' rather than 'whether' we will report them to the Security Council," said the official, speaking on condition of anonymity because he was not authorized to discuss the issue with journalists.

Iran maintains its nuclear program is designed only to generate electricity.

On Sunday, Iran opened the door for U.S. help in building a nuclear power plant — a move designed to ease American suspicions about the program.

Ereli dismissed the offer Monday as "the biggest pipe dream I've ever heard of."

In Israel, a close U.S. ally, officials said Monday they would not rule out a military strike if Iran advances in efforts to develop nuclear weapons.

ElBaradei and the IAEA received the Nobel Peace Prize in Oslo, Norway, on Saturday, for their efforts to control the spread of nuclear weapons.

When accepting the award, ElBaradei said the international community is "losing patience" with Iran over its nuclear program.

Iran state television, meanwhile, reported Monday that Iran had successfully tested surface-to-sea missiles with a range of 68 miles. The report did not say whether the missiles could carry nuclear warheads.