Mitt Romney would respect an Israeli decision to make a unilateral military strike against Iran aimed at preventing Tehran from obtaining nuclear capability, a top foreign policy adviser said as he outlined the aggressive posture the Republican presidential candidate will take toward Iran in a speech in Israel.
Mr 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 near Jerusalem's Old City.
Mr Senor said Mr Romney is careful to note the governor believes preventing nuclear "capability" - not just a nuclear weapon - is critical.
He later clarified his comments in a written statement, saying: "Governor Romney believes we should employ any and all measures to dissuade the Iranian regime from its nuclear course, and it is his fervent hope that diplomatic and economic measures will do so. In the final analysis, of course, no option should be excluded."
Democratic US President Barack Obama has also affirmed the right of Israel to defend itself, but in contrast to Mr Romney, Mr Obama has warned of the consequences of an Israeli strike on Iran.
"Already, there is too much loose talk of war," Mr Obama told the American Israel Public Affairs Committee in March. "Now is the time to let our increased pressure sink in and to sustain the broad international coalition we have built."
Pentagon officials have spoken publicly about the difficulty of such a strike and American officials have expressed concern about the destabilising effect such military action could have in the region, even if carried out successfully.
Mr Romney, like Mr Obama, believes the option of a US attack should also be "on the table". He has said he will do "the opposite" of what Mr Obama would do in his approach to Israel.
"Make no mistake: the ayatollahs in Tehran are testing our moral defences. They want to know who will object, and who will look the other way," Mr Romney plans to say in his speech. "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."