Russia would consider fresh U.S. sanctions—such as curbing the operations of Russian banks or their foreign-currency dealings—a declaration of “economic war,” Prime Minister Dmitry Medvedev has warned. The U.S. announced a new round of sanctions Wednesday that pushed Russia’s ruble to a two-year low. Separate draft legislation introduced last week by Republican and Democratic senators proposes curbs on the operations of several state-owned Russian banks in the U.S. and would bring in restrictions on their use of the dollar. Medvedev said Moscow would take economic, political, or other retaliatory measures against the U.S. if Washington hit Russian banks. “I would not like to comment on talks about future sanctions, but I can say one thing: If some ban on banks’ operations or on their use of one or another currency follows, it would be possible to clearly call it a declaration of economic war,” said Medvedev. Meanwhile, Russia and China teamed up Thursday to object to a U.S. proposal to add a Russian bank, a Moscow-based North Korean banker, and two other entities to a U.N. Security Council blacklist.