WASHINGTON — The head of the U.S. Missile Defense Agency says the Obama administration has discussed declassifying key data on U.S. missile defense to provide it to Russia.

The administration has been exploring how to ease Russian concerns that the U.S. missile defense shield is aimed at countering Russia's nuclear arsenal.

Arms control advocates have suggested that revealing missile interceptor capabilities could provide a breakthrough on an issue that Russia says stands in the way of nuclear arms reductions. But doing so would provoke charges by Republicans that the administration is compromising national security to appease Moscow.

Under questioning at a hearing on Wednesday, the director of the Missile Defense Agency, Vice Admiral James Syring, said he had discussed declassifying data, including the speed of interceptors, with senior U.S. Defense Department officials.

Missile defense has long been a contentious issue between the United States and Russia. The U.S. has said its capabilities are aimed at countering threats from Iran and North Korea. It says its interceptors would not pose a threat to Russia's huge nuclear arsenal.

Obama has twice altered U.S. missile defense plans in Europe that Russia had stridently opposed. He has said the decisions were about better addressing threats. But Republicans have charged that they were aimed at soothing Russian objections.

U.S. Discussing Giving Russia Missile Defense Data