ASHKELON, Israel — A series of public statements and private communications from the Israeli leadership in recent weeks set off renewed concerns in the Obama administration that Israel might be preparing a unilateral military strike on Iran, perhaps as early as this fall.

But after a flurry of high-level visits, including one by Defense Secretary Leon E. Panetta to Israel on Wednesday, a number of administration officials say they remain hopeful that Israel has no imminent plans to attack and may be willing to let the United States take the lead in any future military strike, which they say would not occur until next year at the earliest.

The conversations are part of delicate negotiations between the United States and Israel that have intensified over the past month. On Wednesday they continued with Mr. Panetta, who appeared with the Israeli defense minister, Ehud Barak, and declared that the United States would stand by Israel if Iran developed a nuclear weapon.


In Israel, there remains feverish speculation that Mr. Netanyahu will act in September or early October. Besides the prime minister’s fear that Israel’s window of opportunity will close soon, analysts cite several reasons for the potential timing: Israel does not like to fight wars in winter. Mr. Netanyahu feels that he will have less leverage if President Obama is re-elected, and that if Mr. Romney were to win, the new president would be unlikely to want to take on a big military action early in his term.

“If I were an Iranian, I would be very fearful of the next 12 weeks,” said Efraim Halevy, a former chief of Israel’s intelligence agency and national security adviser.