By Amy Harder 

WASHINGTON--The State Department on Friday named Amos Hochstein as acting special envoy and coordinator for international energy affairs, filling the position at a critical time for the Obama administration's energy diplomacy efforts.

The State Department's Bureau of Energy Resources, which Mr. Hochstein will now lead, has been working closely with European nations to help them become less dependent on Russian natural gas. Unrest in Iraq and other areas of the Middle East has added to concern about stability of the global oil market.

Mr. Hochstein is replacing special envoy Carlos Pascual, who announced in June he was stepping down to join the Center on Global Energy Policy, a research organization at Columbia University founded last year by Jason Bordoff, a former top adviser to President Barack Obama. Mr. Pascual, a former U.S. ambassador to Ukraine had held the position since May 2011.

The rise in domestic oil and natural gas production, which has made the U.S. the biggest producer of both fuels, has changed energy markets throughout the world, Mr. Hochstein testified at a congressional hearing this week.

"This overall sea change in U.S. energy balances has had significant international energy market implications as vast quantities of imported energy once destined for the United States are now consumed elsewhere in the world markets," he said Tuesday in prepared testimony at a Senate hearing on how energy and climate change fuel global conflict.

Mr. Hochstein will also likely be more involved in helping shape the administration's strategy on Russia, though this week he declined to say how energy may factor more into any strategy.

He noted that in the additional sanctions Mr. Obama announced last week, three major Russian energy companies were targeted: the state-controlled Rosneft, Russia's biggest oil producer; OAO Novatek, the second-biggest gas company; and OAO Gazprombank, the bank connected with the country's gas-export monopoly.

"I think it should be clear where we are today, and the fact that there are effects already in the energy sector," Mr. Hochstein said after Tuesday's hearing. "Where we go from here, is really going to depend on Russia's actions."

Mr. Hochstein, who has been deputy assistant secretary for energy diplomacy at the State Department since November 2011, has advised several Democrats throughout his career, including former Sen. Chris Dodd of Connecticut and then-Virginia Gov. Mark Warner, who is now a senator. He also spent several years working for Cassidy & Associates, a Washington, D.C., government-relations firm. His new position is effective Aug. 1.

Write to Amy Harder at amy.harder@wsj.com

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