U.S. officials are concerned that Russian spies may attempt to target Americans and U.S.-based systems using Kaspersky lab, a Russia-based cybersecurity firm, according to a report from ABC News.

In secret memorandum described to ABC News and sent last month from the Senate Intelligence Committee to Director of National Intelligence Dan Coats and Attorney General Jeff Sessions, there is concern that Kaspersky Lab may be at risk of being compromised. The letter urged the intelligence community to address risks posed by the Russian-based security company.

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The memorandum reportedly considered the potential risk posed by Kaspersky products an “important national security issue.”

The Senate Intelligence Committee’s concerned is backed by the Department of Homeland Security, which issued a secret report on Kaspersky Lab to other government agencies in February. The FBI is also investigating ties between Kaspersky Lab and the Russian government, according to ABC News.

U.S. officials are reportedly concerned about the past of several Kaspersky Lab executives, who previously worked for Russian intelligence and military agencies. At the heart of the concern is that the security tools could potentially provide access to state-sponsored hackers, who could target individuals or larger entities that count on Kaspersky software.

The greatest risk, according to experts, is the possibility that Kaspersky Lab products help facilitate a Russian cyberattack aimed at power grids and other key areas of infrastructure within the U.S.

Read: Kaspersky And FireEye Security Products Cracked By Researchers

Products from Kaspersky Lab, a well-respected security firm based in Moscow, are commercially available in big box stores and are used by individuals, businesses and government agencies throughout the U.S., including the Bureau of Prisons. According to the company’s site, it has more than 400 million users around the world, including 270,000 corporate clients.

Kaspersky, for its part, continues to hold that it does not have any “inappropriate” links with the Russian government and said its products are safe to use.

“Kaspersky Lab does not develop any offensive techniques and has never helped nor will help any government in the world with their offensive efforts in cyberspace,” the company said in a statement.

Eugene Kaspersky, the CEO of Kaspersky Lab, has been a person of interest for U.S. intelligence agencies for some time now. He was the subject of a counterintelligence investigation launched by the FBI in 2012, and was reportedly asked to become an informant for the agency—an offer he declined.

In a profile of Kaspersky that was published in Wired in 2012, the security company executive was described as a possible “tool of the Kremlin” because of his ties to the Russian Federal Security Service and his training at KGB-sponsored schools.

Earlier this year, the Russian government charged an employee of Kaspersky Lab—along with two officers in the Federal Security Service—with treason for allegedly cooperating with the U.S. government.