Recent U.S. intelligence reports have raised concerns about Israeli spy agencies eavesdropping on American negotiators working on a peace deal with Iran, amid rising concern over a more general counterintelligence threat by Israel.

Israel and the United States have long known, and tolerated, that each was spying on the other. But an intensified Israeli effort to learn about U.S. positions in talks with Iran has crossed a line, according to some American officials.

The reports include concerns that Israel has stepped up its efforts to eavesdrop on senior American officials, including Steve Witkoff, President Trump’s top negotiator, Elbridge A. Colby, the Pentagon’s top policy official, and one of his main deputies, Michael P. DiMino IV.

Another report, written by the Defense Intelligence Agency and other military intelligence offices and focused on earlier events going back several years, said that the counterintelligence threat level posed by Israel had been increased in recent weeks to the top level, from high to critical. The report, to which the Defense Counterintelligence and Security Agency contributed, outlines various efforts by Israel to spy on American military personnel and government officials.

The reports and the intensified concern about Israeli spying come at an especially sensitive time. Israel and the U.S. have been fighting the war against Iran together, and have never had such close military coordination as they do now, with Israeli military officers working side-by-side with their American counterparts at U.S. Central Command.

The U.S. military is sharing huge amounts of tactical and operational information with its Israeli counterparts. But senior American officials said that Israel is looking for insights into Mr. Trump’s strategy and shifting stances on the peace talks.