Pro-Russian hacktivist groups have claimed responsibility for the recent hacking spree across European grocery stores. Federal agencies are urging hospitals, transportation systems and food retailers to shore up industrial refrigeration systems after a spate of cyberattacks disrupted cooling systems at grocery stores and blood banks across Europe.

The Pentagon also said in a statement last week that it was investigating a string of recent freezer malfunctions at six commissaries on U.S. military bases, though it’s unclear if these incidents are related.

The latest warning from U.S. agencies signals growing concern that these attacks could spread and affect U.S. food refrigeration systems.

The fact sheet — authored by the Cybersecurity Infrastructure Security Agency, the FBI and the departments of Health and Human Services, Agriculture and Transportation — noted that the federal government is “aware of malicious cyber actors targeting industrial refrigeration and cold chain monitoring systems globally.”