WASHINGTON — President Biden and his top officials vowed this week to introduce additional sanctions aimed at impeding Russia’s war efforts against Ukraine. But the administration’s focus is increasingly shifting to the role that China has played in supplying Russia with goods that have both civilian and military uses. As one of the world’s biggest manufacturers of products like electronics, drones and vehicle parts, China has proved to be a particularly crucial economic partner for Russia. Beijing has remained officially unaligned in the war. Yet China, along with countries like…