The United States showed little immediate enthusiasm for a new Iranian proposal that would end the war and reopen the Strait of Hormuz without resolving the impasse over the Islamic Republic's nuclear program.

Iran's latest offer looked “better” than past pitches, Secretary of State Marco Rubio said late Monday, after it was discussed by President Donald Trump and his national security team. But there was little sign that Washington might be willing to abandon its naval blockade and accept the offer.

Energy prices soared again on the negative signals, with the international benchmark price for oil, Brent crude, reaching a three-week high above $111 a barrel early Tuesday.

The Iranian proposal would focus on reopening Hormuz — the vital trade route whose closure has shaken the global economy — and ending the war the U.S. and Israel began two months ago, but table thorny nuclear talks until a later date, a Gulf source and a regional source told NBC News.

The details of the proposal were first reported by Axios.

“Suffice it to say that the nuclear question is the reason why we’re in this in the first place,” Rubio said in an interview with Fox News.

"They’re very good negotiators," he said of Iran, but he said any agreement would have to be one that "definitively prevents them from sprinting toward a nuclear weapon at any point."

Iran maintains that it has no desire to develop a nuclear weapon, but American demands that Tehran halt its enrichment program have been a key roadblock in peace talks.

The Iranian proposal was discussed Monday in a meeting between Trump and his national security team, according to White House Press Secretary Karoline Leavitt, although it was not immediately clear how seriously it was being weighed. ​

“The president’s red lines with respect to Iran have been made very, very clear, not just to the American public, but also to them as well,” Leavitt told reporters. “I wouldn’t say they’re considering it,” she said, adding that Trump would address the subject publicly soon.

Members of the Gulf Cooperation Council will hold a meeting Tuesday where the Iranian proposal will also be discussed, according to two Gulf officials. Kuwait’s state news agency confirmed the group was expected to convene for an exceptional summit in Jeddah on Tuesday.