Israeli Prime Minister Benjamin Netanyahu said today the world has until next summer at the latest to stop Iran before it can build a nuclear bomb.
Mr Netanyahu flashed a diagram of a cartoon-like bomb before the UN General Assembly, showing the progress Iran has made.
He said it has already completed the first stage of uranium enrichment.
Then he pulled out a red marker and drew a line across what he said was a threshold Iran was approaching and which Israel could not tolerate - the completion of the second stage and 90% of the way to the uranium enrichment needed to make an atomic bomb.
“By next spring, at most by next summer at current enrichment rates, they will have finished the medium enrichment and move on to the final stage,” he said.
“From there, it's only a few months, possibly a few weeks before they get enough enriched uranium for the first bomb.”
Israel considers a nuclear-armed Iran to be an existential threat, citing Iranian denials of the Holocaust, its calls for Israel's destruction, its development of missiles capable of striking the Jewish state and its support for hostile Arab militant groups.
Today Mr Netanyahu presented his case to the world just why a nuclear armed Iran would be a danger to many other countries as well.
Casting the battle as one between modernity and the “medieval forces of radical Islam,” Mr Netanyahu said deterrence would not work against Iran as it had with the Soviet Union.
“Deterrence worked with the Soviets, because every time the Soviets faced a choice between their ideology and their survival, they chose survival,” he said.
But “militant jihadists behave very differently from secular Marxists. There were no Soviet suicide bombers. Yet Iran produces hordes of them.”
Mr Netanyahu has repeatedly argued that time is running out to stop Iran from becoming a nuclear power and that the threat of force must be seriously considered.
Israeli leaders have issued a series of warnings in recent weeks suggesting that if Iran's uranium enrichment program continues it may soon stage a unilateral military strike.
This week Iranian leaders suggested they may strike Israeli preemptively if they felt threatened, stoking fears of a regional war.
President Barack Obama has vowed to prevent Iran from becoming a nuclear power but has rejected Mr Netanyahu's demands for setting an ultimatum past which the US would attack.
His administration has urgently sought to hold off Israeli military action, which would likely result in the US being pulled into a conflict and cause region-wide mayhem on the eve of American elections.
Mr Netanyahu's 2013 Israeli deadline could be interpreted as a type of concession, but Israeli officials insisted action was still needed immediately and that in his speech Netanyahu was referring to the absolute point of no return.
Iran insists its nuclear program is for peaceful purposes, but Israel, the US and other western allies suspect otherwise.
Four rounds of UN sanctions have already been placed on Iran.
A UN report last month reinforced Israeli fears, finding that Iran has moved more of its uranium enrichment activities into fortified bunkers deep underground where they are impervious to air attack.
Enrichment is a key activity in building a bomb, though it has other uses as well, such as producing medical isotopes.
While the bulk of Mr Netanyahu's speech dealt with Iran, he also rebuked Palestinian President Mahmoud Abbas, who spoke shortly before him to the UN General Assembly and accused Israel of ethnic cleansing for building settlements in east Jerusalem.
“We won't solve our conflict with libellous speeches at the UN,” Mr Netanyahu said. “We have to sit together, negotiate together and reach a mutual compromise.”
Israel captured the eastern part of Jerusalem from Jordan during the 1967 Mideast War and later annexed it in a move that hasn't been recognized internationally.
The Palestinians claim east Jerusalem as the capital of their future state along with the Gaza Strip and the rest of the West Bank.
In his speech, Mr Abbas also said he had opened talks on a new bid for international recognition at the UN.
The Palestinians will apply to the General Assembly for non-member state status, in stark contrast to last year's failed bid to have the Security Council admit them as a full member state.
If Palestine does become a UN observer state, it will not have voting rights in the world body but will have international recognition as a “state.”
This could enhance the possibility of the Palestinians joining UN agencies and becoming parties to treaties including the International Court of Justice or the International Criminal Court.
Mr Abbas insisted that the new quest for recognition was “not seeking to delegitimize Israel, but rather establish a state that should be established: Palestine.”