Israel has a sovereign right to decide how to deal with Iran's nuclear ambitions whether the United States agrees or not, Joe Biden, the US vice-president, has said.
In an interview on ABC's "This week" programme on Sunday, Biden said Israel can determine for itself how best to deal with the threat of a nuclear-armed Iran.
"We cannot dictate to another sovereign nation what they can and cannot do when they make a determination, if they make a determination, that they're existentially threatened," Biden said.
Binyamin Netanyahu, the Israeli prime minister, has signalled that he agrees with President Barack Obama's end-of-the-year deadline for progress in efforts to engage Iran diplomatically to resolve a dispute over its nuclear programme.
Netanyahu, who took office in March, has said Israel cannot allow Iran to acquire nuclear weapons and has not ruled out a possible military strike against Iran.
Alaeddin Broujerdi, the head of Iran's parliamentary committee on national security and foreign policy, said Tehran was ready to take "real and decisive" action if Israel attacked its nuclear facilities.
"I believe our response will be real and decisive"
Alaeddin Broujerdi, head of Iran's parliamentary committee on national security
"Both the US and Israel are aware of the consequence of an erroneous decision," Broujerdi told reporters at the Iranian embassy in Tokyo.
"I believe our response will be real and decisive," Broujerdi said.
He declined to elaborate.
Israel has said a nuclear-armed Iran would be a threat to its existence, noting calls by Mahmoud Ahmadinejad, the Iranian president, that Israel should be wiped off the map.
Iran denies it is enriching uranium for military purposes, saying its nuclear development is aimed at generating electricity.
Israel bombed a site in Syria in 2007 that US intelligence officials said was a nearly completed nuclear reactor being built with North Korean help.
In 1981, Israel bombed an Iraqi nuclear reactor.
"If the Netanyahu government decides to take a course of action different than the one being pursued now, that is their sovereign right to do that. That is not our choice," Biden said.
"But there is no pressure from any nation that's going to alter our behavior as to how to proceed."
The UN Security Council has imposed three sets of sanctions on Iran for defying its demand to suspend uranium enrichment, which could also be used to produce nuclear weapons.
The United States has joined Russia, China, France, Germany and Britain in inviting Iran to talks to resolve the nuclear dispute.
Meir Dagan, Israel's Mossad intelligence chief, said last month a world embargo had altered the course of Tehran's nuclear programme since 2003, but that Iran could have an atomic weapon by 2014 unless these steps were intensified.