President Joe Biden is sounding the alarm that Russia is “exploring” its options for a possible cyber attack against the U.S. in retaliation for Western sanctions that have crushed its economy following its invasion of Ukraine.

On Monday, the White House released a statement from Biden citing “evolving intelligence” that the Russian government may launch some type of cyber attack on critical U.S. infrastructure. The president urged the private sector to urgently move to tighten their cyber defenses ahead of a possible attack.

“If you have not already done so, I urge our private sector partners to harden your cyber defenses immediately by implementing the best practices we have developed together over the last year,” Biden said in his statement.

“You have the power, the capacity, and the responsibility to strengthen the cybersecurity and resilience of the critical services and technologies on which Americans rely. We need everyone to do their part to meet one of the defining threats of our time,” he added.

By publicly warning companies to act now, the Biden administration is continuing its strategy of getting ahead of any possible covert or clandestine acts by Russia. To date, the administration has disclosed several Russian plots, including a false flag operation in Ukraine and the possibility of Russia deploying chemical weapons after launching its invasion on Feb. 24.

Yet the low number of cyber attacks from Russia in the wake of the war has caught some by surprise. Before the invasion, Russian actors were accused of launching distributed denial of service (DDOS) attacks against Ukrainian government and private servers but the expected level of cyber blitzkrieg has yet to materialize.

But a lack of attacks has not lessened the administration’s sense of urgency. The Department of Homeland Security, together with the FBI, have each warned companies as well as state and local governments about the dangers they face in cyberspace, particularly during times of international turmoil.