US Defense Secretary Robert Gates says although military action against Iran remains an option, the threat of force is not the only way to stop Iran from building a nuclear bomb.
Israeli Prime Minister Benjamin Netanyahu, visiting the U.S. this week, is turning up pressure on the Obama administration to take a tougher line.
If Israel concludes that Tehran is close to a bomb it could launch its own military strike against Iran's nuclear facilities within months.
But Gates rejects the notion that Iran will only listen if it thinks it's about to be attacked.
He says the latest international sanctions are hitting Iran harder than that country's ruling regime had expected, and should be allowed more time. He spoke in Australia.