“For years, Russia and the West have been flying spy missions over each other’s territory and, for years, both sides have been okay with the mutually-agreed-upon snooping. But Russia is taking the spying to the next level, and American lawmakers are worried. Since the 2002 ratification of the Treaty on Open Skies, 34 nations — Canada, America, most of Europe, Russia, and Turkey — have flown observation missions over each other’s territory, largely as a trust-building exercise between the two sides previously divided by the Berlin Wall. The optical sensors onboard the surveillance planes allow all countries in the treaty to ensure that their neighbors aren’t building up troops along their border, or readying for an offensive strike.”
Source: Russia could be using a ‘trust-building exercise’ to send spy planes over North America | VICE News