After a group of Gulf countries led by Saudi Arabia severed diplomatic ties with Qatar Monday, a new report claims Russian hackers may have planted a fake news story suggesting the country’s leader supported Iran – directly contributing to the escalating crisis in the region.

According to a report by CNN, the FBI sent a team of investigators to the Middle East to help Qatari officials look into the reports that a cyberattack resulted in the erroneous statements appearing on the Qatar News Agency on May 23.

Sources with knowledge of the investigation said that the FBI had linked the attack to Russian hackers — though they couldn’t say whether the hack was carried out by a criminal group or was government-backed. CBS echoed CNN’s findings, saying that the investigation is specifically focusing on Russian interference.

The Kremlin denied any knowledge of the attack Wednesday, saying there was “zero proof” of Russian involvement. “We’re getting tired of reacting to unsubstantiated banalities,” Andrei Krutskikh, a Kremlin adviser on cybersecurity, told the Interfax news agency, adding: “Whatever happens it is hackers. It’s a stale claim and as ever there is zero evidence, and conclusions are drawn before the incident is even investigated.”

As well as the FBI, the U.K.’s National Crime Agency is reportedly investigating the attack. A spokesperson told VICE News that the agency “does not confirm or deny investigations.” Qatari officials told CNN that details would be made public once the investigation was concluded.

The alleged attack relates to a story published by the state-run Qatar News Agency on May 23 which reported Qatari emir Sheikh Tamim bin Hamad al Thani speaking at a military graduation ceremony. The emir was quoted as calling Iran a force of stability in the region, talking about Israel favorably, and criticizing Donald Trump for his tough policy on Iran. As well as appearing online, the news agency shared the story on its Twitter and Instagram feeds.

The comments reportedly contributed to the decision by some Gulf countries to cut ties with Qatar earlier this week, accusing the oil-rich country of sponsoring violent extremism and causing regional instability. The Qatari government strongly denies the claims, but the crisis has already impacted several sectors within the country –including travel, shipping, and oil prices. There are also fears of food shortages, given that Qatar imports most of its perishable foods.

The crisis in the region escalated further Wednesday when the UAE decreed that showing support or sympathy for Qatar online was punishable by up to 15 years in jail or a fine of $136,000. “Strict and firm action will be taken against anyone who shows sympathy or any form of bias towards Qatar, or against anyone who objects to the position of the United Arab Emirates, whether it be through the means of social media, or any type of written, visual or verbal form,” the UAE’s attorney general Hamad Saif al-Shamsi said according to Gulf News.

Airlines including Qantas and Etihad have said that Qatari passport holders are barred from travelling via the UAE as a result of government decisions.

While there is still no clear evidence that Russia was involved, U.S. officials suggest that the Kremlin stands to gain significantly by causing rifts between the U.S. and its allies. The Russian government has been accused of using cyberattacks and disinformation campaigns to influence the outcome of the U.S. presidential election, as well as elections across Europe, including the recent French election.

Following Monday’s decision, Trump tweeted that the split with Qatar could be the “beginning of the end to the horror of terrorism,” and appeared to claim credit for the pressure being placed on the country, saying his recent visit to Saudi Arabia was “already paying off.”

On Wednesday however, Trump sought to strike a more inclusive tone. In a phone call with Saudi King Salman, Trump urged the Gulf states to work together to achieve “the critical goals of preventing the financing of terrorist organisations and eliminating the promotion of extremism by any nation in the region,” according to a White House statement.