Israeli President Shimon Peres on Thursday came out against any go-it-alone Israeli attack on Iran, saying he trusted U.S. President Barack Obama’s pledge to prevent Tehran from producing nuclear weapons.

His comments appeared to challenge Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak, who have both raised the prospect of a unilateral Israeli strike, despite assurances from Washington it will not let Iran get the atomic bomb.

“I am convinced this is an American interest. I am convinced(Obama) recognizes the American interest and he isn’t saying this just to keep us happy. I have no doubt about it, after having had talks with him,” Peres told Channel Two television.

“Now, it’s clear to us that we can’t do it alone. We can delay (Iran’s nuclear program). It’s clear to us we have to proceed together with America. There are questions about coordination and timing, but as serious as the danger is, this time at least we are not alone.”

A flurry of comments by Israeli officials and media reports over the past week have put financial markets on edge by appearing to suggest an attack could be launched before the U.S. presidential election in November.

An unidentified top “decision maker”, widely believed to be Barak, told Haaretz newspaper last Friday that Israel “cannot place the responsibility for its security and future even in the hands of its greatest ally”, a reference to the United States.

Peres said in the interview that he did not believe Israel would launch an attack on Iran before November.

As president, Peres, 89, has little political power in Israel. But he has won the respect of many Israelis while serving in the post and his opposition to any unilateral action poses an additional challenge to Netanyahu.

A political source close to Netanyahu issued an angry response to Peres’ comments shortly after the president’s interview was aired.