Russia filed a request Monday to fly a spy plane carrying advanced digital cameras over the United States. The move presents the United States with a dilemma: How does Washington respond at a time when Moscow and Washington are at odds over Syria and Ukraine and senior U.S. defense officials have identified Russia as the No. 1 existential threat to America?

It would be complicated for the United States to block Russia’s request. The Treaty on Open Skies, which was first approved in 1992 and went into effect in 2002, allows signatories to fly unarmed aircraft carrying video and still cameras, infrared scanning devices and certain forms of radar over the territory of other treaty members. Inspections are carried out to make sure the cameras used meet the terms of treaty and are not too powerful. READ MORE