The European Union has heaped more economic sanctions on Russia, adding to U.S. President Donald Trump's new punitive measures the previous day against the Russian oil industry. Russian President Vladimir Putin responded by warning that the measures were an "unfriendly act" by Washington that could backfire against the U.S. by fueling oil prices. The American and European sanctions are intended as part of a broadened effort to choke off the revenue and supplies that fuel Moscow's invasion of Ukraine, compelling Putin to negotiate an end to the war. Speaking to reporters in Moscow, Putin said the new U.S. sanctions were serious but will not significantly impact its economy. Ukrainian President Volodymyr Zelenskyy hailed the new restrictions.