Russia's central bank is promising to support financial institutions hit by U.S. sanctions as stocks took a tumble on opening in Moscow.

In an online statement, the bank promised to "take adequate measures" to support targeted institutions. Russia's state-owned VTB bank — Russia's second-largest — was trading down 1.2 percent on Wednesday morning.

Other major banks that were left unscathed by sanctions — such as the country's largest, Sperbank — were trading higher.

U.S. officials said Tuesday that roughly 30 percent of Russia's banking sector assets are now constrained by sanctions. The move comes after Malaysia Airlines Flight 17 was shot down over East Ukraine. Western officials accuse pro-Russian separatists of bring down the plane with a missile supplied by Moscow.


Pace reported from Washington.

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