The Israeli Prime Minister, Benjamin Netanyahu, has said he is ready to order a strike on Iran if international sanctions do not stop its nuclear programme.
"I am, of course, ready to press the button if necessary," he said.
Speaking on Israeli television, Mr Netanyahu also indicated Israel was prepared to act unilaterally.
His government has failed to get the US to set a clear "red line" for military action against Iran.
This has put a strain on relations with the administration of President Barack Obama.
Channel Two interviewed the prime minister as part of an investigative report detailing Israel's efforts to stop Iran from what it says is a drive to develop a nuclear weapon.
Iran insists its nuclear programme is purely for peaceful purposes.
The Channel Two report said that in 2010, Mr Netanyahu and his defence minister, Ehud Barak, had given orders for the military to get ready to attack Iran within hours if required.
The programme described this as "the closest Israel has come to attacking Iran".
The orders were later withdrawn in the face of opposition from two top security officials at the time - chief-of-staff Lt Gen Gabi Ashkenazi and the head of the intelligence service, Mossad, Meir Dagan.
According to the programme Gen Ashkenazi considered such an attack on Iran, "a strategic mistake" because of the risk of a war, while Mr Dagan deemed it "illegal", saying a full cabinet decision was needed. Both men have since retired from their posts.
When Mr Netanyahu was asked about the reported exchanges he did not comment directly.
"In the final reckoning, the responsibility lies with the prime minister and as long as I am prime minister, Iran will not have the atomic bomb," he said.
"If there's no other way, Israel is ready to act."
In the documentary, there was also criticism of the handling of the Iranian nuclear threat from the former Israeli Prime Minister, Ehud Olmert. He suggested that the current government had jeopardised its close relationship with Washington.
Mr Olmert is considering making a political comeback ahead of a general election on 22 January.
Like its US ally, Israel has consistently refused to rule out a military option to prevent Iran from obtaining a nuclear bomb. It believes such a weapon would threaten its existence.