U.S. Secretary of State Hillary Rodham Clinton is in Bulgaria, urging the country to break its energy dependence on Russia by diversifying its oil and gas supplies.
U.S. officials say Clinton will use her visit to promote alternatives to existing pipeline routes as well as developing new energy sources. They say eastern Europe's reliance on Russia for energy leaves it vulnerable to "unhealthy" political pressure from Moscow.
Russia drew Washington's fury on Saturday when it vetoed a U.N. Security Council resolution on Syria.
Clinton will also encourage the former Soviet satellite to share its experiences in moving to democracy with Arab nations emerging from authoritarian rule. She will also urge Bulgaria to improve conditions for minority populations.
Clinton flew to Bulgaria after attending an international security conference in Munich.