US presidential hopeful Mitt Romney would "respect" an Israeli decision to strike Iran to stop the Islamic Republic developing a nuclear weapon, a senior aide to the Republican candidate said.
In the latest stop on his three-nation foreign tour, Romney has been vigorously promoting his pro-Israel credentials ahead of the November US presidential poll.
During a trip to Jerusalem, Mr Romney's senior national security aide Dan Senor told reporters that: "If Israel has to take action on its own in order to stop Iran from developing that (nuclear) capability, the governor would respect that decision."
The White House candidate has been holding talks with Israeli Prime Minister Benjamin Netanyahu and President Shimon Peres.
Mr Romney is also due to meet Israeli opposition politicians and Palestinian Prime Minister Salam Fayyad, but he will not meet Palestinian President Mahmoud Abbas.
US President Barack Obama has sought to dissuade Israel from a unilateral attack on Iran to allow time for tough sanctions to take a toll on the Islamic Republic's economy and further isolate the country.
Mr Obama has said the US holds open the option of military operations against Iran but has insisted now is not the time for an attack, either by the US or Israel.
Mr Senor later expanded on his remarks, saying Mr Romney felt "we should employ any and all measures to dissuade the Iranian regime from its nuclear course".
It was Mr Romney's "fervent hope that diplomatic and economic measures will do so" and "no option should be excluded", Mr Senor said.
Speaking later in Jerusalem, Mr Romney declared the city to be the capital of the Jewish state, adding that the US has "a solemn duty and a moral imperative" to block Iran from achieving nuclear weapons capability.
"Make no mistake, the ayatollahs in Iran are testing our moral defences. They want to know who will object and who will look the other way," Mr Romney said.
"We will not look away nor will our country ever look away from our passion and commitment to Israel."
Mr Romney is hoping that a tough stance on Iran will be a vote-winner in the forthcoming election.
He has previously accused Mr Obama of undermining Israel and boosting its enemies.
While not explicitly ruling out military action, Mr Obama has been keen to stress a preference for putting pressure on Iran through non-military means.
In recent weeks, several senior US officials have held talks in Jerusalem, among them US Secretary of State Hillary Clinton, Mr Obama's top counter-terrorism adviser John Brennan and Clinton's deputy William Burns.
And US defence chief Leon Panetta is due in Israel next week for top-level talks, with Iran likely to play a central role in his discussions
The first leg of Mr Romney's trip, in London, was judged a PR disaster after he was widely criticised for questioning London's Olympic preparations on the eve of the Games.
He initially said some aspects of the planning for London 2012 had been "disconcerting".
But after his comments were challenged by figures including London Mayor Boris Johnson and Culture Secretary Jeremy Hunt, he backtracked and said he expected the Games to be "very successful".