With Ukraine holding Russia off longer than many U.S. officials had expected, President Biden now faces a great unanswered question — how to give Vladimir Putin an off-ramp to avoid even greater calamity.

Why it matters: A cornered, humiliated Putin could unleash untold pain on the world, from cyberattacks to nuclear threats. After enacting brutal sanctions, the White House now must consider how the invasion can end without a new catastrophe.

Between the lines: Nobody knows what Putin would accept.

Many officials fear that we are heading into a very dangerous period — the punishing Western sanctions pushing an autocrat into a corner.