Outside of the borders of Ukraine, show Putin the steel and determination of NATO. While the alliance isn’t going to go to war in Ukraine, it must strengthen our defenses in the east. Activate the NATO Response Force and deploy it into nations on the Ukrainian and Russian borders; increase the level of intelligence gathered and shared across the alliance; conduct a new round of border defense exercises; deploy NATO’s Standing Naval Task Force into the Black Sea; and aggressively conduct air policing around the borders of the Alliance, especially in the Arctic which Putin values greatly. And it would be a good time to quietly encourage Finland and Sweden—both of whom have powerful, professional, and capable militaries—to join the alliance.

Finally, there is a strong case to be made that the battlefield may shift to cyber. Moving tanks, jet fighters, and armored personnel carriers full of troops is expensive, and Putin’s financial reserves, while significant, are not unlimited. But electrons are a “free good” in terms of costs, and he may choose to attack Ukraine directly (especially its electric grid) or even conduct a horizontal escalation against the U.S. and NATO. The U.S. and our partners in cyber must be ready to “go offensive” to stop Putin. This may end up being the most dangerous part of the conflict.