If Iran does not accept international proposals to roll back its nuclear programme by next month, it faces an imminent Israeli strike, a newspaper article said.
In an opinion piece on Sunday authored by Micah Zenko who is a political scientist with expertise in national security issues, the Los Angeles Times said Israel will act alone to stop the Islamic Republic from developing a nuclear weapon.
Under the proposals, Iran should suspend its uranium enrichment programme in exchange for a UN Security Council commitment to forgo a fourth round of economic and diplomatic sanctions.
Quoting Michael Mullen, chairman of the US Joint Chiefs of Staff, the newspaper said: "The window between a strike on Iran and their getting nuclear weapons is a pretty narrow window."
However, if Iran does not budge, Israel would attack its suspected nuclear weapons facilities without even informing the US, the newspaper said.
President Obama will learn about the operation from CNN rather than the CIA and Israel would rather explain later than ask for approval in advance of launching pre-emptive attacks, the newspaper said.
Those hoping that the Obama administration will be able to pressure Israel to stand down from attacking Iran as diplomatic efforts drag on are mistaken, the LA Times said.
It said Israel never informed the US before carrying out such four major military operations in the past.
In October 1956, Israel, with Britain and France, attacked Egypt to take control of the Suez Canal. But the then Israel envoy Abba Eban never gave any hint of the impending attack to US Secretary of State John Foster Dulles who had grilled the envoy just a day before about Israel's military build-up on the border with Egypt.
In June 1967, Israel started the Six-Day War without informing Washington, despite President Johnson's insistence that Israel consult with him before taking action.
On June 7, 1981, Israel never informed the US when it destroyed the Iraqi nuclear reactor at Osirak just before it was to be fuelled to develop the capacity to make nuclear weapons-grade plutonium.
The then Israeli Prime Minister Menachem Begin had called the attack "a precedent for every future government in Israel... Every future Israeli prime minister will act, in similar circumstances, in the same way," the newspaper said.
Again in September 2007, Israeli aircraft destroyed a North Korean-supplied plutonium reactor in Al Kibar, Syria, without informing the US.
These episodes demonstrate that if Israel sees Iranian nuclear weapons an existential threat "it will be deaf to entreaties from US officials to refrain from using military force", the newspaper said.