U.S. President Joe Biden’s threatened sanctions far exceed previous measures to curb Russian President Vladimir Putin, but they have not stopped Putin from ordering Russian forces into rebel-held territory in Eastern Ukraine. This begs the question whether the severe measures the United States, the United Kingdom, and the European Union have threatened to take are enough of a redline to stop Putin from going further. In the current era of great power competition, economic sanctions as instruments of statecraft face the ultimate test.