President Biden has tried to walk a careful line on Ukraine: keeping Kyiv in the fight against its Russian invaders while also keeping the U.S. and NATO out of it. His policies are aimed at making the invasion as costly as possible for Russian President Vladimir Putin while avoiding a wider war between nuclear powers.

That is probably the best that can be done, given that Russia’s interest in Ukraine vastly exceeds ours, however horrific the world rightly finds Putin’s aggression. But it does leave Biden open to the criticism that he should be doing more to help Ukraine achieve victory or to deter Putin. And there is a risk that his current approach will merely prolong the war, leading to more death and destruction.

So far, it has been easy for Biden to ignore such criticism, because it has mainly come from the type of hawks who brought us the Iraq war, a folly the president supported himself as a member of the Senate but has since regretted. Sen. Chris Coons, the man who now holds Biden’s Senate seat and a liberal Democrat, will prove harder to ignore.