The US would not necessarily join in were Israel to launch a military strike against Iran’s nuclear program, an unnamed source in the Obama Administration told Israel’s Channel 2 News on Monday.

The US feels a profound commitment to the defense of Israel, and so could be relied upon to protect Israel defensively from the consequences of an Israeli attack on Iran, the TV channel quoted the source as saying. But the thrust of the US source’s message to Israel, the TV report said, was “don’t rely on us to finish the job.”

Israeli media has been full of reports in recent days, based on leaks and off-the-record briefings by senior figures, suggesting that Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak are close to deciding on an Israeli attack to thwart Iran — despite opposition from the US, and from current and former domestic security chiefs.

On Monday, White House spokesman Jay Carney said the US was committed to giving talks with Tehran a chance to bear fruit.

“We continue to believe there is time and space for diplomacy, the opportunity remains for Iran to take advantage of this process,” Carney told reporters, AFP reported.

Carney said he believed talks between the five UN Security Council powers plus Germany, and Iran, should continue.

The negotiations were cut off in the spring after failing to produce any breakthroughs in several rounds of meeting.

A second Israeli TV report on Monday night went so far as to specify the ostensible timeframe for a possible Israeli attack, based in part on a tentative meeting scheduled between Netanyahu and President Barack Obama.

Netanyahu is set to meet the president — in Washington, rather than as previously thought at the UN General Assembly in New York — between September 28 and October 1. The prime minister, Channel 10 News reported Monday, could not possibly order an Israeli strike on Iran prior to that meeting, where the Iranian threat would presumably be the main subject of discussion. Neither could he order an attack before his tentatively scheduled address to the General Assembly a few days earlier, on September 27 — his last appeal to the international community for firmer action to thwart Iran, according to Channel 10.

The timeframe for an Israeli attack, the report suggested, would thus be sometime between October 2 and the presidential elections on November 6. Immediately after the US elections, Israel could presumably not defy a newly elected president. And fairly soon after that, it might be too late for Israel to stop Iran because of the Iranians’ progress and the limitations of Israel’s military capacity.

Channel 10 went on to predict the likely consequences of an Israeli attack in terms of retaliatory missiles fired by Iran and its allies such as Syria, Hezbollah in Lebanon and Hamas in the Gaza Strip.

While Israel’s conflict with Hezbollah in 2006 saw 4,500 rockets and missiles fired into Israel, an Israeli attack on Iran would prompt the firing of 50,000 missiles into Israel, the report said, citing what it said were “assessments in Jerusalem.” The death toll would be estimated 500 Israelis, it said, citing a figure mentioned in the past by Barak.

The Maariv daily reported on Monday morning that, were Israel to attack Iran, Washington would provide Israel with an air defense “umbrella” against the anticipated retaliation by Tehran and its proxies.

Messages passed from Republican and Democrat policy makers in Washington to Israeli counterparts suggest that should Israel decide to bomb Iran in advance of the US presidential elections in November, Obama would order the American armed forces to join in the military effort, the paper said.

Such an intervention, the sources explained, would all but guarantee Obama a second term in office. If he chose not to act, the president would likely be handing the office over to the Republicans, they said.

Advisers close to Republican candidate Mitt Romney and Israeli ambassador to the US Michael Oren were among those who passed the messages between Washington and Jerusalem, Maariv claimed. The Israeli embassy in Washington declined to respond to the report.