Ukrainian President Volodymyr Zelensky, visibly shaken by evidence of the Russian military’s atrocities against Ukrainian citizens in the recently liberated suburbs of Kyiv, on Sunday condemned the slaughter as genocide. The Biden administration has been more cautious: On Monday, national security adviser Jake Sullivan said, “We have not yet seen a level of systematic deprivation of life of the Ukrainian people to rise to the level of genocide.” He promised to “continue to monitor” the situation.

Yet genocide is unfolding before our eyes. Often called “the crime of crimes,” genocide is considered the absolute nadir of human behavior. Activists and politicians tend to apply this label to anything they deplore, even to the vaccination of children against the coronavirus. That degrades the crime, cheapening it. As a scholar of the Holocaust and a descendant of Holocaust survivors, I am well aware of the need for caution, and in the past have criticized the governments of many post-Soviet states — including Ukraine, where I was born — for misusing the term. Not now.

Contrary to popular perceptions, shaped by the Holocaust and Rwanda, perpetrating genocide does not require large numbers of victims. The intent and logic of targeting are the key. The 1948 U.N. Convention on the Prevention and Punishment of the Crime of Genocide defines genocide as “acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group.”

This definition is not without drawbacks. An updated version might expand protected groups to include those defined by gender, age or sexual identity. The document also does not define, in absolute numbers or percentages, when killings cross the line into genocide; “in whole or in part” is open to interpretation. And proving intent is difficult, especially if orders were given orally or were camouflaged by bureaucratic jargon.

The violence in Ukraine has none of these issues. Bucha, near Kyiv, is just one town, but the horrifying murders there are a part of a broader pattern. Deliberate targeting of Ukrainian civilians, especially those who self-identify as Ukrainians, with bombardment, murder and abduction have been recorded in other parts of Russian-occupied Ukraine.