More than two million Russian and Ukrainian troops have been killed or wounded in the four years that Russia has been waging war against its neighbor, according to a new study, a bleak milestone as Russia’s assault grinds on. The study, published on Wednesday by the Center for Strategic and International Studies in Washington, said Russia has borne the heavier toll, with 1.4 million troops killed or wounded since February 2022, when Russia invaded Ukraine. Of that total, 450,000 were killed, a number that is four times greater than U.S. fatalities in all wars combined since World War II. Ukrainian...