Russia pulls out of US-sponsored 2016 Nuclear Security Summit

Russia has informed the United States that it will boycott the 2016 Nuclear Security Summit, diplomats said, potentially stripping the meeting of one of its key participants and hurting efforts initiated by President Barack Obama to reduce the threat of nuclear terrorism.

Officials had already revealed on Monday that Moscow was absent from last week's initial summit planning session in Washington, but had left it unclear whether Russia planned to attend the summit itself.

On Tuesday, two diplomats said the boycott applied to the 2016 meeting as well. They cited as their source a diplomatic note from Moscow to the US and other nations planning to participate. The diplomats spoke on condition of anonymity because they are not allowed to discuss confidential information.

One of the diplomats said the note expressed opposition to the summit because of its political nature. He cited the note as saying that any meeting on nuclear security should be on a technical level and convened not by a nation but by the UN's International Atomic Energy Agency.

Russia has participated in such summits in the past. But the diplomat, who is familiar with Moscow's stance, said it already had reservations while attending the last meeting in March in The Hague. He did not specify, but added that the "changed political atmosphere" - shorthand for Russia-US tensions over Ukraine - added to the Kremlin's decision to stay away.

In Moscow, Russian Foreign Ministry officials did not immediately respond to a request for comment.