(CNN) -- With Osama bin Laden dead, Iranian supreme leader Ayatollah Ali Khamenei is now the biggest threat to peace in the world, Israeli Prime Minister Benjamin Netanyahu told CNN on Thursday.
"He runs the country and he is infused with fanaticism, Iran's supreme leader was more worrying than its president, Mahmoud Ahmadinejad, as the Islamic republic pursues a controversial nuclear program".
"If the Iranian regime gets atomic bombs, it will change history, The future of the world -- the future of the Middle East -- is certainly at stake."
"Those sanctions might work if the international community makes it clear that there is a credible military option if sanctions don't work".
The death of bin Laden weakens extremists worldwide, Netanyahu said:
"When the world's number one terrorist... is brought to justice and eliminated, it tells terrorists everywhere there's a price and you will pay it, and that's good."
The Israeli prime minister said he has not seen the photos of bin Laden dead, but he's not concerned by that.
"I don't think anyone is really questioning that Osama bin Laden has been killed."
Netanyahu also expressed cautious optimism about the "Arab Spring" revolutions that have shaken the region, but warned they could be hijacked by extremists, as was the case with the 1917 Russian revolution and 1979 Iranian revolution.
"Something very big is happening here, a convulsion... We would like to see the triumph of democracy... that's something that will guarantee the peace".
But he also warned that the instability could cut both ways.
"The biggest threat is the possibility that a militant Islamic regime will acquire nuclear weapons -- or that nuclear weapons could acquire a militant Islamic regime".
He refused to be drawn on whether Syrian President Bashar al-Assad should resign as the country's security forces clamp down on protesters.
But, he said, "this butchering of civilians must stop now."