Israeli Prime Minister Benjamin Netanyahu says a "strong and credible" military threat is needed to prevent Iran from developing a nuclear weapon.
Speaking in Jerusalem, Netanyahu said international sanctions and other diplomatic efforts had proven ineffectual in persuading Iran to open its nuclear program to inspection.
"We have to be honest and say that all the sanctions and diplomacy so far have not set back the Iranian program by one iota," 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."
Netanyahu's comments came during a meeting with the U.S. Republican presidential hopeful Mitt Romney, who earlier signaled he would support an Israeli preemptive military strike on Iran.
Romney's senior national security aide, Dan Senor, told reporters in Israel that Romney would "respect" a decision by Israeli officials to use military force against Iran to stop work on its nuclear program, which Israel believes could be used to launch a missile attack on the Jewish state.
Speaking during his meeting with Netanyahu, Romney said he looked forward to further discussions on curbing Iran's nuclear activity.
"Your perspectives with regards to Iran and its efforts to become a nuclear-capable nation are ones which I take with great seriousness," Romney said. "And I look forward to chatting with you about further actions that we could take to dissuade Iran from their nuclear folly."
He also said that Jerusalem is the capital of Israel.
Romney, who is on the second leg of a three-country tour aimed at boosting his foreign-policy credentials ahead of the U.S. presidential vote this November, went on to meet with Israeli President Shimon Peres.
He was also due to visit the West Bank city of Ramallah, although he had no meeting scheduled with Palestinian leader Mahmud Abbas.
Romney's visit comes as Israel's "Haaretz" newspaper has published a report claiming President Barack Obama's national security adviser has already informed Netanyahu of a U.S. plan to attack Iran if diplomatic efforts fail to convince Tehran to curb its nuclear program.
U.S. officials have yet to comment on the "Haaretz" report, which quotes an unnamed U.S. official as saying the adviser, Thomas Donilon, described the plan over dinner with Netanyahu earlier in July.
The Obama administration has traditionally urged restraint on Iran issues, calling on Israel to back diplomatic efforts to resolve the nuclear standoff.
On a visit to Jerusalem this month, U.S. Secretary of State Hillary Clinton said Israel and Washington were "on the same page" with respect to Iran and said the United States "will use all elements of American power to prevent Iran from obtaining a nuclear weapon.
Iran says its program is solely for peaceful purposes.
Based on reporting by Reuters, AFP, and AP