US President Barack Obama warned against a premature attack on Iran, while Israeli leader Benjamin Netanyahu insisted his country had the right to self-defense and needed room to maneuver.
But in an apparent nod to Netanyahu ahead of key White House talks on Monday, Obama said if sanctions failed to curb Tehran's atomic ambitions, US military action against Iranian nuclear facilities should not be ruled out.
"I think that the Israeli government recognizes that, as president of the United States, I don't bluff," Obama told the Atlantic Monthly magazine in remarks published Friday.
"I also don't, as a matter of sound policy, go around advertising exactly what our intentions are. But I think both the Iranian and the Israeli governments recognize that when the United States says it is unacceptable for Iran to have a nuclear weapon, we mean what we say."
US strategy included isolating Tehran politically, sanctions and diplomacy, Obama said.
"And it includes a military component. And I think people understand that," he added.
On his way to Washington, Netanyahu arrived Friday in Canada against a backdrop of fears that Israel could unilaterally strike suspected Iranian nuclear sites.
Speaking alongside Canadian Prime Minister Stephen Harper during a visit to parliament in Ottawa, Netanyahu had tough words but was careful not to appear to be pressuring his US ally.
"I have not set red lines and we are not seeking to set red lines to the United States," he said in Hebrew.
"We do ask to reserve the freedom of action of the state of Israel in the face of threats to wipe us off the map. I think that is something that any state would demand for itself."
Tehran insists its nuclear program is for civilian purposes, but Western nations suspect Iran is trying to secretly develop atomic weapons and is close to achieving its goal.
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Netanyahu says all options remain on the table concerning action on Iran, whose President Mahmoud Ahmadinejad has repeatedly questioned Israel's right to exist.
To allay suspicions, Netanyahu says Iran must dismantle its underground nuclear facility in Qom, stop uranium enrichment and eliminate all enriched material beyond what it needs to make medical isotopes or generate nuclear power.
"And when I say all the material, I mean all the material, from 3.5 percent up," Netanyahu said.
Obama warned, however, that a premature military strike could inadvertently help the Iranian regime.
"At a time when there is not a lot of sympathy for Iran and its only real ally (Syria) is on the ropes, do we want a distraction in which suddenly Iran can portray itself as a victim?" Obama said.
Regardless of Israel's role, "it would still be a profound national-security interest of the United States to prevent Iran from getting a nuclear weapon," the president argued.
He also spoke of the "profound" risks of an Iranian nuclear weapon falling into terrorists' hands, and warned of "the prospect of a nuclear arms race in the most volatile region in the world, one that is rife with unstable governments and sectarian tensions.
"And it would also provide Iran the additional capability to sponsor and protect its proxies in carrying out terrorist attacks because they are less fearful of retaliation," he said.
Israeli President Shimon Peres told the New York Times Thursday that the United States must make it clear to Iran that "all options are on the table."
"We need a total and clear commitment that the catastrophe of Iran will not create an impossible situation," Peres said, acknowledging there was disagreement over where to draw the red line that would spark military action.
Obama, who addresses the powerful American Israel Public Affairs Committee (AIPAC) on Sunday, said essentially "our goals are in sync" adding "we've got Israel's back. And that's something that I constantly try to reinforce and remind people of."
But he admitted to differences with Netanyahu, describing their relationship as one focused on business and noting their different political traditions.
Obama will briefly meet Peres -- a fellow Nobel Peace Prize winner -- "backstage at AIPAC," a senior US official said, speaking on condition of anonymity. There were no details on what the two would talk about.