JERUSALEM (AP) -- Mitt Romney would back an Israeli military strike against Iran aimed at preventing Tehran from obtaining nuclear capability, a top foreign policy adviser said early Sunday, outlining the aggressive posture the Republican presidential candidate will take toward Iran in a speech in Israel later in the day.
Romney has said he has a "zero tolerance" policy toward Iran obtaining the capability to build a nuclear weapon.
"If Israel has to take action on its own, in order to stop Iran from developing the capability, the governor would respect that decision," foreign policy adviser Dan Senor told reporters ahead of the speech, planned for late Sunday near Jerusalem's Old City.
Romney believes the option of a U.S. attack should also be "on the table."
The Obama administration also hasn't ruled out the military option, and U.S. President Barack Obama has so far been relying on sanctions and diplomatic negotiations to discourage Iran from building a nuclear bomb.
For its part, Iran says it is not interested in nuclear weapons and its nuclear program is for peaceful, civilian purposes.
The Israelis are considering a strike because they fear Iran could be moving its nuclear enrichment sites further underground, out of reach of the weapons Israel has available.
An Israeli newspaper reported Sunday that the Obama administration's top security official briefed Israel's prime minister earlier this month on U.S. plans for a possible attack on Iran.
According to the Haaretz daily, National Security Adviser Tom Donilon sought to reassure Israel that Washington is prepared to act militarily should diplomacy and sanctions fail to pressure Iran to abandon its nuclear enrichment program.
An Israeli government spokesman did not respond to a request for comment. A U.S. Embassy spokesman couldn't be reached.
Iran's nuclear program has become the most pressing problem for the U.S. and Israel, and one that is a far easier cause to take up for an American administration in an election year. Republicans have consistently criticized Obama for putting too much pressure on Israel in the peace process and being too weak on Iran.
Obama rejects the criticism, and his aides point to what they call unprecedented U.S.-Israeli security cooperation.
Senor was previewing the speech Romney plans in Jerusalem after he spends the day meeting with Israeli officials.
"Make no mistake: the ayatollahs in Tehran are testing our moral defenses. They want to know who will object, and who will look the other way." Romney says in an excerpt of his speech provided to reporters. "My message to the people of Israel and the leaders of Iran is one and the same: I will not look away; and neither will my country."
Over the course of the day, Romney will confront some of the world's most difficult peace and security challenges as he looks to demonstrate to Jewish and evangelical voters back home that he's a better friend to Israel than Obama.
Romney faces high stakes as he begins his talks with top Israeli officials and meets with the Palestinian prime minister. Mindful of polls back home that show a tight presidential contest, the former one-term Massachusetts governor is looking to burnish his foreign policy credentials and prove his mettle as a possible commander in chief.
The trip is a chance for Romney to draw implicit contrasts with Obama and demonstrate how he would lead America on the world stage.
But Romney arrived in Jerusalem Saturday night after a difficult few days in Britain, where he made the mistake of criticizing the country's Olympic Games and raised the hackles of his hosts. The gaffe undermined the stated goal of his weeklong journey through Britain, Israel and Poland: emphasizing America's ties with longstanding allies.
"In a time of turmoil and peril in Israel's neighborhood, it is important that the security of America's commitments to Israel will be as clear as humanly possible. When Israel feels less secure in the neighborhood, it should feel more secure of the commitment of the United States to its defense," Romney said in a Friday interview with the Israeli newspaper Haaretz.
Romney has pledged not to criticize Obama while on foreign soil, honoring longstanding American tradition of leaving politics at the water's edge. But his aide's announcement of Romney's willingness to express support for an Israeli strike while in Jerusalem represents an effort to contrast the two presidential opponents.
In interviews with Israeli newspapers ahead of his arrival, Romney has both criticized Obama and commented on policy details.
"Iran is closer to nuclearization than it was when President Obama took office. It is hard to feel that the events of the last three and a half years have strengthened America's posture and promoted the prospects of peace," Romney told Hayom, a conservative Israeli publication bankrolled by billionaire casino mogul Sheldon Adelson. Romney was still in the U.S. when he spoke to the paper, though his remarks weren't published until Friday, when he was already abroad.
In the interview with Ha'aretz, Romney urged caution in supporting rebel forces in Syria. He's previously said the U.S. should do more to arm the opposition there, but reports this week say Islamist terror groups could now be an element of rebel forces, prompting caution from U.S. officials.
"I think it is important for the responsible nations of the world to seek to understand which forces in Syria represent real change, rather than the kind of destruction that might occur if al-Qaeda were to seize the development of chaos and assert leadership in some significant way in Syria," Romney said Friday.
Romney will meet with Israeli Prime Minister Benjamin Netanyahu and a host of Israeli security officials. He'll also meet with Israeli President Shimon Peres and the leaders of Israel's political opposition. Romney will also hold a meeting with Palestinian Prime Minister Salam Fayyad, though his advisers say he didn't have time to meet with Palestinian Prime Minister Mahmoud Abbas.
Romney plans to spend the evening dining at Netanyahu's home - the Israeli leader invited Romney and his wife to break the fast for the Jewish holiday Tisha B'Av. The holy day, celebrated Sunday, commemorates the destruction of two temples in Jerusalem. Romney and Netanyahu have known each other since both were young businessmen at Boston Consulting Group in the 1970s.
On Monday, Romney plans a fundraiser with top American supporters in Israel, some guests have flown in from the U.S. specifically for the event. His campaign has barred reporters from covering his comments to the 50 or so wealthy backers who will gather at the luxurious King David Hotel - all of whom will have donated $50,000 or raised at least $100,000. Keeping the remarks private is a change from how Romney handles fundraisers in the United States, where a group of reporters are allowed into events held in public spaces like hotels.
Expected among the attendees is Adelson, who has pledged to spend $100 million to defeat Obama and who has given millions to a third-party group supporting Romney's presidency.
While Romney is left to implicit contrasts with his Democratic opponent, Obama has been focusing on Israel, signing legislation on Friday increasing military and civilian ties between the U.S. and Israel. And he authorized the release of an additional $70 million in military aid for Israel, a previously announced move that appeared timed to Romney's trip.