Russia is the world’s largest producer of the metal, a crucial ingredient for catalytic converters in cars, capacitors in electronics, dental crowns, jewelry, and much else besides. As the West threatens tougher sanctions against Russia for its perceived provocations in eastern Ukraine, Russia may try to do equal damage with trade restrictions of its own. Limiting palladium exports may be a useful weapon—harsher than the travel bans imposed on key Western officials, but not as provocative as oil or gas embargoes.