Israel Defense Forces Chief of Staff Gabi Ashkenazi, on his first official visit to Washington, warned Thursday that Israel would not rule out any course of action regarding Iran's nuclear ambitions, Israel Radio reported.

"We are all united in the view that Iran needs to be prevented from obtaining a nuclear weapon. There is no doubt that diplomatic activity and sanctions are preferable, but we all understand - we and the Americans - that we need to prepare all options," the radio report quoted Ashkenazi stating after meeting with senior United States officials.

Western nations accuse Iran of seeking to develop nuclear weapons under the cover of its civil nuclear program. Iran denies that, saying its atomic program is to generate power so it can export more of its valuable oil and gas.

On the first day of his trip Wednesday, the IDF chief warned that it was crucial to block what he called "Iranian aggression" in the Middle East.

"We are are witnessing, I believe, a paradigmatic change in the Middle East in which radical countries and elements are trying to [install] a new order to replace the traditional national, secular one that exists today," Ashkenazi said in a brief speech at the Israeli Embassy.

Israel and Washington accuse Iran of fomenting violence in Iraq and of supplying arms to Palestinian militants and to Lebanon's Hezbollah, which the United States regards as a terrorist organization.

"At the center of this radical axis is Iran, who seeks to achieve its regional aspiration of hegemony by upsetting the existing balance of power," Ashkenazi told the embassy, accusing Iran of backing "terror organizations and radical groups" and of pursuing nuclear arms "to project power within the region and beyond."

"I believe it is therefore crucial that we block Iranian aggression, which [may] in turn weaken the radicalization process in the region presently being manifested in such places as Iraq, Afghanistan, Lebanon and in the Palestinian territories," he added.

Ashkenazi made no reference to speculation about the possibility of an Israeli strike on Iranian nuclear facilities. Israel carried out an air strike last year on a suspected Syrian nuclear reactor.

The IDF chief met with U.S. Vice President Dick Cheney on Wednesday, as well as senior congressmen and John Negroponte, the deputy secretary of state. On Thursday he was set to meet with his counterpart at the Pentagon, Chairman of the U.S. Joint Chiefs of Staff, Admiral Michael Mullen.

Meanwhile, Democratic presidential hopeful Barack Obama pledged to Prime Minister Ehud Olmert Wednesday that if elected, he will coordinate his policy on Iran with Israel.

Senior U.S. officials, while saying they never take any option off the table - code for the possibility of a military strike - have played down speculation about a U.S. military strike against Iran over its nuclear program.

But speculation that Israel could bomb Iranian nuclear installations has grown since it reportedly carried out a large-scale air force drill over the Mediterranean last month that was widely seen as a "dress rehearsal" for a possible raid on Iran.

The United States is pursuing a diplomatic path to try to persuade Iran to suspend its uranium enrichment program, a process that can produce fuel for power plants or, if greatly refined, for nuclear weapons.

So far, neither Western offers of economic incentives nor three UN Security Council sanctions resolutions have convinced Iran to suspend uranium enrichment.

U.S. officials have said repeatedly they are focused on the diplomatic track and, along with other permanent members of the UN Security Council and Germany, have given Iran two weeks to respond to a fresh offer of incentives from the so-called P5+1 group if it suspends uranium enrichment.

Ashkenazi's schedule on Wednesday included meetings with U.S. Vice President Dick Cheney, White House national security adviser Stephen Hadley, Deputy Secretary of State John Negroponte and key members of Congress. On Thursday, he is to meet Admiral Mike Mullen, chairman of the Joint Chiefs of Staff.