Mitt Romney, the presumptive US Republican presidential nominee, has held high-level talks in Israel about how to handle fears over Iran's nuclear ambitions, on a visit aimed at burnishing his foreign policy credentials.
"Like you, we are very concerned about the development of nuclear capabilities on the part of Iran and feel it is unacceptable for Iran to become a nuclear-armed nation," Romney said after meeting President Shimon Peres on Sunday.
"The threat it would pose to Israel, the region and the world is incomparable and unacceptable."
Romney would support Israel if it were to decide it had to use military force to stop Iran from developing a nuclear
weapon, a senior aide said ahead of the planned meetings in Jerusalem.
"If Israel has to take action on its own, in order to stop Iran from developing that capability, the governor would respect
that decision," Dan Senor, Romney's senior national security aide, told reporters travelling with the candidate.
The Republican challenger, who will face off against President Barack Obama in November's US election, flew in from Britain late on Saturday for a one-day visit expected to focus on Iran's nuclear programme, which Israel and much of the West believes is a covert attempt to develop atomic weapons.
"Iran and its effort to become a nuclear-capable nation [is one] which I take with great seriousness, and look forward to chatting with you about further actions that we can take to dissuade Iran from their nuclear folly," Romney told Prime Minister Binyamin Netanyahu earlier on Sunday in remarks carried on Israeli public radio.
He also said the two could discuss "developments about the region" including in Syria and Egypt.
Netanyahu told him it was important to have "a strong and credible military threat" because sanctions and diplomacy "so far have not set back the Iranian programme by one iota".
"I think it's important to do everything in our power to prevent the Ayatollahs from possessing that capability," he said.
"And that's why I believe that we need a strong and credible military threat, coupled with the sanctions, to have a chance to change that situation."
Romney was also to meet Salam Fayyad, the Palestinian prime minister, later on Sunday and give a statement on foreign policy.