The Federal Bureau of Investigation (FBI) is warning of a heightened likelihood of Iranian cyber-attacks following the escalation of tension between the U.S. and Iran. This follows the warning last week by the Department of Homeland Security (DHS). The FBI and DHS issued a bulletin to law enforcement groups warning of potential physical and cyber-attacks on the U.S.

The FBI stated that “the FBI is aware of the continued possibility that retaliatory actions could be taken against the United States and its interests abroad” based upon increased scanning and reconnaissance.

According to Chris Krebs, head of DHS’ cybersecurity division, U.S. companies should be looking for Iranian cyber-activity, particularly related to industrial control systems and software that supports the systems. Krebs tweeted “[P]ay close attention to your critical systems, particularly ICS. Make sure you’re also watching third party accesses!”

Other security professionals have noted that companies should be proactively looking for threats to their systems that could have originated from Iran. According to Secretary of State Mike Pompeo, Iran has “a deep and complex cyber capability.”