The Biden administration is arming Ukraine with weapons that can do serious damage to Russian forces, and, unlike early in the war, U.S. officials don’t appear worried about Moscow’s reaction. In the past several months, Washington has detailed tranches of new drones, harder-hitting missiles and deadly rocket systems as part of billions of dollars pledged to the former Soviet country. The clear support is a far cry from the early days of the war, when the U.S. government seemed hesitant to list exactly what was being sent into Ukraine so as not to tip off or draw the ire of...