Streets in Aleppo are filled with the bombed, burned, and shot bodies of innocent civilians—the result of the latest atrocities perpetrated by a regime that has killed over 450,000 people with the assistance of its murderous allies. US Ambassador to the UN Samantha Power placed these atrocities in their proper historical context:

Aleppo will join the ranks of those events in world history that define modern evil, that stain our conscience decades later. Halabja, Rwanda, Srebrenica, and, now, Aleppo. To the Assad regime, Russia, and Iran, your forces and proxies are carrying out these crimes. Your barrel bombs and mortars and airstrikes have allowed the militia in Aleppo to encircle tens of thousands of civilians in your ever-tightening noose. It is your noose. Three Member States of the UN contributing to a noose around civilians. It should shame you. Instead, by all appearances, it is emboldening you. You are plotting your next assault. Are you truly incapable of shame? Is there literally nothing that can shame you? Is there no act of barbarism against civilians, no execution of a child that gets under your skin, that just creeps you out a little bit? Is there nothing you will not lie about or justify?

Assad and the other architects of mass murder may not feel shame, but the international community should. The Obama administration should. The Vatican should. Everyone who has spent years opposing viable concrete action to protect civilians should. These crimes have played out in real time. I see pictures of slaughtered civilians in my social media feeds every day. No one can claim they didn’t know what was happening. They chose to commit mass murder. And we chose not to act. This should elicit a sense of shame from everyone who has a basic sense of decency or even a minimal commitment to morality.