U.S. lawmakers have been discussing the standoff with Iran, which is facing referral to the United Nations Security Council over its nuclear program.

In his address Tuesday, President Bush sent a strong signal to the Iranian government that the United States and other nations cannot permit Iran to obtain nuclear weapons.

That brought a sharp response from Iran's President Ahmadinejad, who has declared that the Iranian government will resist attempts to restrict its nuclear development program.

Iran has long maintained that its nuclear efforts have no military objective.

On Capitol Hill, the Iran nuclear issue was the subject of a congressional hearing and remarks by various lawmakers from both political parties.

Experts appearing before the House Armed Services Committee differed on the best ways of dealing with the problem.

One of them, George Perkovich, of the Carnegie Endowment for International Peace, discussed a Russian proposal on defusing the situation.

"The point is that you get established that Iran does not get to do enrichment on Iranian soil, and the price you have to pay for that is the Russian proposal, and in that process you get the Russians on board with the stick if Iran [doesn't comply]," he said.  "It seems to me that in the world we are living in, that is pretty good, because without the Russians we don't get anything."

The Russian proposal involves an offer to enrich uranium for Iran on Russian soil in exchange for an agreement from Tehran to resume a moratorium on its nuclear activities.

Concern has been rising on both sides of Capitol Hill, with House and Senate lawmakers watching developments closely.

Democratic Senator Diane Feinstein, in an interview with CNN, underscored the importance of cooperation from Russia and China in diplomatic efforts.

Republican Senator Trent Lott called the prospect of nuclear weapons in Iranian hands,  "very scary and dangerous."

The subject also came up during a news conference by Democratic Congressman, John Murtha who was asked about the option of military action.

"I see the president not being willing to take [the military option off the table], because that is just one of the things you do when you are negotiating," said Mr. Murtha.  "But I tell you it is going to be very difficult for anybody to believe with the strain we have on us now, that we could react."

President Bush has said for some time that no options can be ruled out in dealing with the Iranian situation.

Since statements by Iran's president calling for the destruction of Israel and describing the Holocaust as a myth, lawmakers in Congress have grown more alarmed.

Last year, legislation calling for sanctions on Iran gained the support of more than two-thirds of the House of Representatives, although it never became law.

The legislation proposed strengthening and codifying U.S. sanctions on Iran for its sponsorship of terrorism and unconventional weapons production, and authorizing U.S. assistance to peaceful pro-democracy and human rights groups in Iran, and independent broadcasts to Iran.

The support it received reflects lawmaker's strong emotions about the threat many believe Iran poses in the region.  The legislation also reflects what many members of Congress believe is the desire of Iranians for political change.