A Russian general was killed today by a bomb on a Moscow street. Ukraine claimed responsibility for what appears to be one of the most brazen assassinations since Russia’s full-scale invasion nearly three years ago.

The general, Igor Kirillov, 54, died along with an aide after an explosive device planted in a scooter was detonated this morning, Russian authorities said. Kirillov was the head of Russia’s radioactive, chemical and biological defense forces. Yesterday, Kyiv had blamed him for the “massive use of banned chemical weapons” in Ukraine.

While other Russian generals have died during the war, Kirillov is the highest-ranking military official to have been killed inside Russia. Ukraine’s security service shared a video of the attack.

A senior American official said the U.S. was not informed about the assassination ahead of time and warned that the killing might be counterproductive by inciting a reaction from Vladimir Putin.

In related news: The reality has set in on Capitol Hill that, with Donald Trump poised to take office, the era of U.S. military support for Ukraine is coming to an end.