U.S. spies caught Russian intelligence officers boasting that they had convinced the oil-rich United Arab Emirates “to work together against US and UK intelligence agencies,” according to a purported American document posted online as part of a major U.S. intelligence breach.

U.S. officials declined to comment on the document, which bore known top-secret markings and was viewed by The Associated Press. The Emirati government on Monday dismissed any accusation that the UAE had deepened ties with Russian intelligence as “categorically false.”

But the U.S. has had growing concerns that the UAE was allowing Russia and Russians to thwart sanctions imposed over the invasion of Ukraine.

The document viewed by the AP includes an item citing research from March 9 with the title: “Russia/UAE: Intelligence Relationship Deepening.” U.S. officials declined to confirm the document's authenticity, which the AP could not independently do. However, it resembled other documents released as part of the recent leak.

The Justice Department has opened an investigation into the possible release of Pentagon documents that were posted on several social media sites. They appear to detail U.S. and NATO aid to Ukraine and U.S. intelligence assessments regarding U.S. allies that could strain ties with those nations.

Some of the documents may have been altered or used as part of a misinformation campaign, U.S. officials said. National Security Council spokesman John Kirby on Monday urged caution, “since we know at least in some cases that information was doctored.”

Referring to the main successor agency of the Soviet-era KGB, the document seen by the AP says: “In mid-January, FSB officials claimed UAE security service officials and Russia had agreed to work together against US and UK Intelligence agencies, according to newly acquired signals intelligence." Signals intelligence refers to intercepted communications, whether telephone calls or electronic messages.

“The UAE probably views engagement with Russian intelligence as an opportunity to strengthen growing ties between Abu Dhabi and Moscow and diversify intelligence partnerships amid concerns of US disengagement from the region,” the assessment concluded, referring to the UAE capital.

It’s not clear if there was any such agreement as described in the UAE-Russia document, or whether the alleged FSB claims were intentionally or unintentionally misleading.

But American officials are speaking out increasingly about a surge in dealings between the UAE and Russia.

A U.S. Treasury official, Assistant Secretary Elizabeth Rosenberg, in March singled out the UAE as a “country of focus." She said businesses there were helping Russia evade international sanctions to obtain more than $5 million in U.S. semiconductors and other export-controlled parts, including components with battlefield uses.

U.S. intelligence officials in recent years have pointed to possible links between the UAE and the Wagner Group, a Russian paramilitary group closely associated with the Kremlin and active in Ukraine and several African countries. In 2020, the U.S. Defense Intelligence Agency assessed “that the United Arab Emirates may provide some financing for the group’s operations.”

Andreas Krieg, an associate professor at King’s College in London, on Monday called the UAE “the most important strategic partner for Russia in both the Middle East and Africa.” The head of Russia’s Foreign Intelligence Service, Sergey Naryshkin, held extensive meetings with UAE leaders in Dubai in 2020.

Russia and the UAE share similar outlooks in some key conflicts in the Middle East and North Africa, and the influx of Russians into the UAE since Russia launched its war in Ukraine also has strengthened ties between the two, said Kristian Ulrichsen, a Middle East expert at Rice University's Baker Institute. But the reference to teaming up against U.S. and British intelligence agencies is surprising, said Ulrichsen.

Russian intelligence officials “probably have an interest in describing something in those terms,” he said. “If that was the way the UAE was describing it, I'd certainly take it ... quite differently.”

A U.S. official separately has told the AP that the United States also was worried about Russian money coming into Dubai's red-hot real estate market.

And in October, federal prosecutors in New York announced charges against two Dubai-based Russian men and others accused of stealing military technology from U.S. companies, smuggling millions of barrels of oil and laundering tens of millions of dollars for the oligarchs surrounding Russian President Vladimir Putin.

Prosecutors in that case quoted one of the Dubai-based Russians as assuring his partners “there were no worries” about using a UAE financial institution for the transactions. “This is the (worst) bank in the Emirates,” he was quoted as saying, using an expletive. “They pay to everything.”

In a statement Monday to the AP about the apparent intelligence document, the United Arab Emirates said UAE officials had not seen the document and claims regarding the FSB were “categorically false.”

“We refute any allegation regarding an agreement to deepen cooperation between the UAE and other countries' security services against another country,” the statement said. “The UAE has deep and distinguished relations with all countries, reflecting its principles of openness, partnership, building bridges, and working to serve the common interests of countries and peoples to achieve international peace and security.”

The leak of the purported document comes as Emirati officials have recalibrated their foreign policy in the Middle East after a series of attacks attributed to Iran. Attacks claimed by Yemen’s Iranian-backed Houthi rebels hit Abu Dhabi in 2022, killing three people and leading locally stationed American forces to respond with Patriot missile fire.

In the time since, and as Emiratis perceived America’s presence waning in the region after its chaotic withdrawal from Afghanistan, the UAE reached a détente with Iran. That’s even as the United States maintains multiple military bases and stations thousands of troops and weaponry in the region, including at Abu Dhabi’s Al Dhafra Air Base. Dubai’s Jebel Ali Port remains the busiest U.S. Navy port of call outside of the continental U.S.

The UAE also remains one of the few places still running daily, direct flights to Moscow after Russia’s 2022 invasion of Ukraine. That has seen money, megayachts and Russian citizens come into the UAE, an autocratic federation of seven sheikhdoms on the Arabian Peninsula. However, it hasn’t been a full embrace.

Relations between the U.S. and the UAE have seesawed over the past decade, as Abu Dhabi ruler Sheikh Mohammed bin Zayed Al Nahyan cemented his power. Under the Trump administration, the UAE diplomatically recognized Israel.

In the deal's wake, the UAE sought but has yet to receive advanced American F-35 fighter jets under President Joe Biden. Meanwhile, the Emirates has criticized Israel over the escalating violence between Israel's hard-right government under Prime Minister Benjamin Netanyahu and the Palestinians.