Israel was the country that provided the US with the classified intelligence that President Donald Trump shared with the Russians, The New York Times reported Tuesday, casting a dark shadow over one of the closest intelligence-sharing partnerships.

According to a Washington Post report on Monday, Trump disclosed top secret intelligence to Russian Foreign Minister Sergey Lavrov and Moscow’s ambassador to the US, Sergey Kislyak concerning a terror plot by the Islamic State involving the use of laptops on aircraft.

Some of that intelligence came from Israel, unnamed US officials told the Times.

The Times reported that, according to a current and a former American official, it was information that Israel relayed to the United States. The intelligence was deemed too classified to share with other United States allies, let alone a rival state like Russia, the Washington Post’s sources said. Russia is the main supporter of Syrian President Bashar Assad, and an ally of Iran, one of Israel’s principal adversaries.

Israeli Ambassador to the US Ron Dermer speaks to media at Trump Tower, Thursday, Nov. 17, 2016, in New York. (AP Photo/Carolyn Kaster)

Israeli Ambassador to the US Ron Dermer speaks to media at Trump Tower, Thursday, Nov. 17, 2016, in New York. (AP Photo/Carolyn Kaster)

The country supplying the intelligence to the United States was identified in the Post story only as “an ally that has access to the inner workings of the Islamic State.”

Israel and the United States are close allies whose leaders often refer to the countries’ “special relationship.” The United States provides Israel with some $4 billion of defense assistance annually, and the countries share intelligence and participate in joint military exercises. Trump will be visiting Israel next week on his first foreign trip as president.

Ron Dermer, Israel’s ambassador to the United States, did not comment directly on the report.

“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,” Dermer said in a statement.

“The revelation that Mr. Trump boasted about some of Israel’s most sensitive information to the Russians could damage the relationship between the two countries,” The Times said. “It also raises the possibility that the information could be passed to Iran, Russia’s close ally and Israel’s main threat in the Middle East.”

BuzzFeed quoted what it described as two unnamed Israeli intelligence officers saying that the incident represented Israel’s “worst fears confirmed.”

“We have an arrangement with America which is unique to the world of intelligence sharing. We do not have this relationship with any other country,” said one officer.

“There is a special understanding of security cooperation between our countries,” he said. “To know that this intelligence is shared with others, without our prior knowledge? That is, for us, our worst fears confirmed.”

A report earlier in the year foreshadowed just such an incident and concerns in the intelligence community.

In January, the Yedioth Ahronoth newspaper in Israel reported that US intelligence officials warned their Israeli counterparts that Trump’s ties to Russia could pose a security threat, and described a meeting between US and Israeli intelligence officials in which the Americans indicated to Israel they should be cautious in sharing information with Trump’s White House. The paper reported that the Americans assessed that Russia had some kind of leverage over Trump, but did not go into details.

A handout photo made available by the Russian Foreign Ministry on May 10, 2017 shows US President Donald J. Trump (C) speaking with Russian Foreign Minister Sergei Lavrov (L) and Russian Ambassador to the U.S. Sergei Kislyak during a meeting at the White House in Washington, DC. (HO / RUSSIAN FOREIGN MINISTRY / AFP)

A handout photo made available by the Russian Foreign Ministry on May 10, 2017 shows US President Donald J. Trump (C) speaking with Russian Foreign Minister Sergei Lavrov (L) and Russian Ambassador to the U.S. Sergei Kislyak during a meeting at the White House in Washington, DC. (HO / RUSSIAN FOREIGN MINISTRY / AFP)

On Tuesday, US National Security Adviser H.R. McMaster said in a White House briefing that Trump was not aware of the source of the intelligence that he disclosed to the Russians, suggesting that Trump could not have compromised confidential sources.

McMaster added that none of the US officials present for the president’s Oval Office meeting with Lavrov last week “felt in any way that that conversation was inappropriate.” He used the words “wholly appropriate” nine separate times.

“In the context of that discussion, what the president discussed with the foreign minister was wholly appropriate to that conversation and is consistent with the routine sharing of information between the president and any leaders with whom he is engaged,” he said.

He also cast some of Trump’s revelations as information that was available from publicly available “open-source reporting.”

National Security Adviser H. R. McMaster speaks during a press briefing at the White House in Washington, DC on May 16, 2017. (AFP PHOTO / Olivier Douliery)

National Security Adviser H. R. McMaster speaks during a press briefing at the White House in Washington, DC on May 16, 2017. (AFP PHOTO / Olivier Douliery)

Earlier Tuesday, Trump took to Twitter to defend his reported decision to give classified intelligence information to Russia, in a statement that appeared to contradict earlier denials by White House officials, who had said he had not let slip any secrets.

Trump said he has “the absolute right” to share information and had done so in order to encourage the Russians to “greatly step up their fight against ISIS & terrorism.”

The information Trump disclosed, according to the Washington Post, was provided by an unnamed US partner — now said to be Israel — through an intelligence-sharing arrangement so secret, its details are unknown to some within the government. The officials said Trump’s revelations endangered cooperation with the US ally, which is reported to have access to the workings of the Islamic State.

“If that partner learned we’d given this to Russia without their knowledge or asking first, that is a blow to that relationship,” a US official told the Washington Post.

The New York Times, which later picked up the story, said the ally had previously shared information with the US only to see it leaked, and had warned US officials that it may cut off access to such information if it is shared too widely.

Trump “revealed more information to the Russian ambassador than we have shared with our own allies,” another US official said.

The bombshell Washington Post report came as Moscow’s alleged interference in last year’s US presidential election was back in the spotlight following Trump’s shock firing of FBI chief James Comey, whose agency was investigating Russia’s possible collusion with aides to the Republican billionaire.