U.S. worries Russia could step up North Korea support to fill China void

By Michelle NicholsUNITED NATIONS (Reuters) - As the United States pressures China to enforce United Nations sanctions on its ally North Korea, Washington is concerned that Russia could provide support to Pyongyang and fill any vacuum left by Beijing, U.S. Ambassador to the United Nations Nikki Haley said on Tuesday."I'm concerned that Russia may backfill North Korea," Haley told U.S. lawmakers in Washington.