Warner foresees two ways a digital war could draw in NATO countries, including the United States:

Putin deploys cyber weapons inside Ukraine that take on a life of their own and spread to NATO member states. This has happened before — most notably in 2017, when Russia’s NotPetya malware was unleashed in Ukraine and ended up causing billions of dollars in damage to companies worldwide.

Putin retaliates against the West’s toughest sanctions by ordering direct cyberattacks targeting infrastructure inside the U.S. and other NATO allies. The U.S. government issued an alert this week urging businesses and agencies to protect their “most critical digital assets,” citing “the potential for the Russian government to consider escalating its destabilizing actions” beyond Ukraine.