Ukrainians and their allies continue to urge Congress to declare the Russian invasion of their country a genocide, a step lawmakers and the U.S. State Department have been reluctant to formally take so far, despite mounting evidence.

The latest effort came this week when Razom for Ukraine, a U.S.-based civil society group, released a letter from 50 genocide scholars, human rights activists and international lawyers to the leaders of the House Foreign Affairs Committee asking them to bring up a genocide declaration that has languished in the House since last year.

President Joe Biden said in the early weeks of the war that it was a genocide , but his administration has since been much more cautious about the label, which has a legal definition under a 1948 international treaty.

In February, however, the administration got a little closer, with Secretary of State Antony Blinken declaring that Russia had committed crimes against humanity.

These acts are not random or spontaneous; they are part of the Kremlins widespread and systematic attack against Ukraines civilian population, Blinken said.