Israeli Prime Minister Benjamin Netanyahu. Thomson Reuters Israel reportedly was the source of the highly classified intelligence President Donald Trump disclosed to Russian diplomats last week. It was also said to have been warned months ago by US intelligence officials not to share classified information with Trump, for fear it might be leaked to Russia.

"Donald Trump's upcoming inauguration as the next president of the United States is causing Israeli intelligence officials to lose sleep as well," Ronen Bergman reported for the Israeli news outlet Ynetnews on January 12.

"Discussions held in closed forums recently raised fears of a leakage of Israeli intelligence top-classified information, clandestine modus operandi, and sources, which have been exposed to the American intelligence community over the past 15 years, to Russia — and from there to Iran," the report said.

According to The Washington Post, that has played out almost exactly — though it is unclear whether the Russians have relayed that intelligence to Iran.

The Post reported Monday night that Trump's disclosures to Russian Foreign Minister Sergey Lavrov and Ambassador Sergey Kislyak "jeopardized a critical source of intelligence on the Islamic State" and "had been provided by a US partner through an intelligence-sharing arrangement considered so sensitive that details have been withheld from allies and tightly restricted even within the US government."

BuzzFeed News got confirmation on Tuesday from two Israeli officials that the shared intelligence was about an ISIS plot to smuggle laptop bombs on airplanes.

US officials briefed their Israeli counterparts before Trump's inauguration about their belief that Russian President Vladimir Putin had "leverages of pressure" over Trump, according to Bergman. Trump's meeting with Lavrov and Kislyak last week was reportedly requested by Putin.

Bergman reported:

"The Americans implied that their Israeli colleagues should 'be careful' as of January 20, Trump's inauguration date, when transferring intelligence information to the White House and to the National Security Council (NSC), which is subject to the president. According to the Israelis who were present in the meeting, the Americans recommended that until it is made clear that Trump is not inappropriately connected to Russia and is not being extorted — Israel should avoid revealing sensitive sources to administration officials for fear the information would reach the Iranians."

US President Donald Trump and Netanyahu. AP Photo/Evan Vucci Lt. Gen. H.R. McMaster, the national security adviser, has denied that Trump revealed intelligence sources and methods in his conversations with the Russians. But when asked by a reporter on Tuesday whether Trump revealed the city in which a US ally detected an ISIS plot, McMaster replied that what Trump discussed with the Russians about the Islamic State "was nothing you would not know from open-source reporting." Experts say the revelation could jeopardize that ally's intelligence-gathering sources and methods.

"All of you are familiar with the threat from ISIS," McMaster said. "All of you are very familiar with the territory it controls. If you were to say, 'Hey, from where do you think a threat might come, from territory that ISIS controls,' you would probably be able to name a few cities.

"It had all to do with operations that were already ongoing and had been made public for months," he said.

But Trump relayed to the Russian diplomats "code-word information," one of the highest classification levels used by the US intelligence community, according to The Post.

Israel's ambassador to the US, Ron Dermer, said in a statement: "Israel has full confidence in our intelligence-sharing relationship with the United States and looks forward to deepening that relationship in the years ahead under President Trump."

But Israeli officials who spoke to BuzzFeed News said Trump's disclosure was "our worst fears confirmed."

"There has to be trust for this sort of arrangement," one official said. "I cannot speak for Israel's entire security apparatus, but I would not trust a partner who shared intelligence without coordinating it with us first."