Nearly 1 million Russian soldiers have been killed or injured in the country’s full-scale invasion of Ukraine, according to a new study, a grisly measure of the human cost of Russian President’s Vladimir Putin’s unprovoked three-year assault on its neighbor.

Western military planners have been carefully studying Ukraine’s successes since the war began. Destroying $7 billion worth of aircrafts with cheap drones is yet another one.

Russia’s invasion force is expected to suffer more than 1 million casualties by the summer as a result of the Ukraine war, with around 250,000 troops already confirmed dead, according to a new study.