WASHIGNTON (NEXSTAR) — As tensions rise between Ukraine and Russia, the United States and NATO allies are bolstering in their cyber defenses, fearing the possibility of Russian retaliation.

A cyber security expert at Virginia Tech believes that Russia is likely to try to retaliate against the U.S. online for our government’s support of Ukraine.

“I think we should be very concerned,” David Simpson said.

NATO Secretary General Jens Stoltenberg says NATO Allies are ramping up their cyber defenses and are “very aware that Russia has been responsible for cyber attacks before.”

U.S. Joint Chiefs Chairman General Mark Milley says the U.S. military is prepared and has a significant amount of capabilities to defend and do what is necessary to protect the country.

This week, an internal memo from the U.S. Department of Homeland Security said Russia could target critical infrastructure in the U.S.

Simpson said Russia’s goal would be “to have us be angry at each other and to not be confident in our government.”

Last year, President Joe Biden signed an executive order to bolster cyber security within the federal government and private sector, but Simpson says the effort may have been too little, too late.

Simpson advises American companies and workers to be on alert and “be ready to spot malicious activity early and then invoke the response plan.”