Iran is "over a year or so" from getting a nuclear bomb, US President Barack Obama said in an interview on Thursday a week before visiting Israel, warning that the military option remained on the table.
In an interview with Israel's Channel 2 television, Obama laid out a clear timeline for Iran to acquire a military nuclear capacity, while insisting that Washington would not wait until the last minute to take action to stop it.
"We think that it would take over a year or so for Iran to actually develop a nuclear weapon, but obviously, we don't want to cut it too close," he said in an exclusive 25-minute interview with the private TV station.
Obama is due to arrive in Israel on March 20 for a three-day visit, his first since being elected president in 2008, on a trip which will also take him to the Palestinian territories.
Should diplomacy fail, all options remained "on the table" for stopping Iran, he said.
"My message to (Israeli Prime Minister Benjamin Netanyahu) will be the same as before: if we can resolve it diplomatically, that's a more lasting solution. But if not, I continue to keep all options on the table," he said.
Signup to our newsletter and follow us on Facebook and Twitter!
Asked if there was a realistic option that he would order an attack on Iran's nuclear sites, he said: "When I say that all options are on the table, all options are on the table and the United States obviously has significant capabilities.
"But our goal here is to make sure that Iran does not possess a nuclear weapon that could threaten Israel or could trigger an arms race in the region -- that would be extraordinarily dangerous at a time when obviously there are already a lot of things going on," he said.
Washington, Israel and much of the West believe that Iran's nuclear programme of uranium enrichment is a cover for a weapons drive, a charge denied by Tehran.
Iran possessing a nuclear weapons would be "a red line" for the United States, Obama said, insisting that he would have the necessary support within his cabinet should a military strike become necessary.
"I think my cabinet is prepared for a whole range of contingencies," he told the channel.
"Secretary (of State John) Kerry and Secretary (of Defence Chuck) Hagel share my fundamental view that the issue of Iran's nuclear capability is an issue of US national security interest as well as Israel's national security interest."
Israel, the Middle East's sole if undeclared nuclear power, has refused to rule out the option of a pre-emptive military strike on the Islamic republic's nuclear facilities, and Netanyahu has said the question of Iran would be a top priority in his talks with Obama in Jerusalem.