http://www.thedailybeast.com/articles/2014/04/18/pentagon-moves-to-block-russian-spy-plane-in-american-skies.html

“Russian surveillance planes already fly over America, thanks to a long-standing treaty. But a new, ultra-sophisticated spy plane has U.S. military and intelligence bosses spooked.”

“The State Department on the other hand has argued the United States should live up to the treaty’s obligations and approve the new Russian aircraft. The decision to certify the planes and their sensors has been pending since late last year, long before the Ukraine crisis began. One senior U.S. official said, “This isn’t just an issue between the United States and Russia. Our allies and partners depend on this treaty for insight into Russia because they don’t have the same capabilities as the United States.”

“The Russians use the aircraft today to monitor U.S. nuclear weapons as part of arms control agreements between both countries. The Russian planes, according to U.S. officials involved in the dispute, contain a new sensor package that would allow Moscow to surveil American nuclear assets with a level of precision and detail that makes U.S. military and intelligence leaders deeply uncomfortable.”