Afghanistan and Ukraine are very different conflicts, but we must still learn from our previous failures. Just as we made a moral and strategic error rushing out of Afghanistan, it would be a terrible mistake to withdraw support for Ukraine while Russian aggression continues. It will make Russia Europe’s dominant military power and undermine liberal democracy. To avoid this, NATO allies need to stay the course, argues Laurie Bristow. The article is based on Bristow's experiences as Ambassador to Afghanistan, where he was the last man on the ground when the Taliban invaded. The story is told in his memoir, Kabul: Final Call.