“We get briefings, but they are empty,” one Israeli official contended the other day. Perhaps so, but when Israeli officials start discussing the details of the current negotiations — from how long an agreement would stay in place before Iran would be free to produce as much enriched uranium as it wants to the proposed engineering changes to a heavy-water reactor that could produce bomb-grade plutonium — the officials seem quite up-to-date.

According to one American official, the concern is that Israeli officials, mindful that they are talking to audiences at home, in the United States and particularly in Congress, know how to pick out one or two details that seem particularly incriminating.

“They tell part of the story, like how many centrifuges we might consider letting the Iranians hold,” one American official said, refusing to speak on the record because the White House and the State Department insist on secrecy, for fear that leaks of any kind could kill a deal here or in Tehran. “What they don’t tell you is that we only let them have that many centrifuges if they ship most of their fuel out of the country.”

The Israelis say Mr. Obama has regularly frozen them out, starting with the secret round of negotiations with the government of President Hassan Rouhani that brought about a temporary freeze in Iranian activity and led to the present talks. “It makes us question in Israel, are they open with us or are they trying to hide from us?” Gen. Yaakov Amidror, Mr. Netanyahu’s former national security adviser, said Tuesday, arguing that trust between the allies had been badly damaged.

In public, Israeli officials complain about what Yuval Steinitz, the minister of intelligence and strategic affairs, called the United States’ general approach to the negotiations, which is to give up on the idea of dismantling all of Iran’s nuclear enrichment capability. In fact, even the George W. Bush administration had given up on that idea, conceding that there was no way to reach a deal without Iran retaining at least a face-saving amount of enrichment capability.

But a few years ago, American officials defined that face-saving amount as a few hundred centrifuges. The offer made to Iran last fall was about 4,500 centrifuges — provided that most of the country’s fuel was shipped out to Russia, so Iran could not race to make a bomb.

There is now talk of raising that figure to 6,500 centrifuges, but only if Iran reconfigures them in a way that would greatly lower their efficiency. The Energy Department’s national laboratories, which make the fuel for American nuclear weapons, have been churning out ideas that would assure, in their view, that Iran would not be able to make a bomb’s worth of fuel in less than a year — the standard Mr. Kerry set for a viable agreement.