Sen. Angus King, I-Maine, speaks during a Senate Armed Services Committee hearing on the conclusion of military operations in Afghanistan and plans for future counterterrorism operations, Tuesday, Sept. 28, 2021, on Capitol Hill in Washington. Credit: Patrick Semansky / AP

U.S. Sen. Angus King warned Thursday that the U.S. and its allies should be on “high alert” for potential Russian cyberattacks as the war in Ukraine continues to escalate.

A week after Russia first invaded Ukraine, Russian leader Vladimir Putin has not seen the quick victory he likely hoped for. But King, speaking with reporters virtually on Thursday afternoon, expressed concern the Russian leader could become more aggressive as the conflict drags on and U.S.-backed economic sanctions take their toll.

“As the sanctions become more effective on the Russians and their economy is really collapsing — the ruble is now worth less than one cent — it’s very likely that Vladimir Putin is going to lash out,” King said.

King, an independent who caucuses with Democrats, said a potential cyberattack would not necessarily target military capabilities, but could hit the private sector or critical infrastructure like water or transportation systems. He said shoring up U.S. Cyber Command would be a good use for some of the additional money the White House has requested in light of the conflict.

The senator highlighted the importance of the international community’s aggressive targeting of the Russian economy, including countries like Switzerland that have typically maintained greater neutrality.

But he warned that there were limits on what the West can do to support Ukraine, with some actions — such as establishing a no-fly zone over Ukraine — likely to be read as an escalation, something the U.S. and its allies do not want to risk given that Russia has nuclear weapons.

“We don’t want to concede, we don’t want to appease by any means, but we also don’t want to provoke a catastrophic nuclear confrontation that would be just literally unimaginable,” he said.

King, who sits on the Senate Intelligence Committee, said he had not seen intelligence pertaining to Putin’s mental state. But he suggested Putin had made some “bad mistakes” that had led to the conflict, including shutting out opposing opinions from advisers that may have given him more honest insight on the resistance Ukraine would mount.

He said Putin had also underestimated the strength of response from the U.S. and its NATO allies. In the past week, Western nations have effectively taken major Russian banks out of the global banking system, closed airspace to Russian flights and begun to seize the assets of powerful oligarchs, among other actions.