WASHINGTON (Reuters) - A White House official said on Tuesday it is "appalling" that a public official in Russia would suggest the death penalty for Americans captured in Ukraine.

       The Kremlin said on Tuesday that the U.S. citizens captured in Ukraine were subject to court decisions and did not rule out that they could face the death penalty.

       "It's appalling that a public official in Russia would even suggest the death penalty for American citizens ... in Ukraine," said John Kirby, National Security Council coordinator for strategic communications.

       (Reporting by Trevor Hunnicutt and Nandita Bose in Washington; editing by Jonathan Oatis)