Space begins at an elevation of 330,000 feet. For some reason, anything above this has been classified again, for some reason, as “outer space shall be free for exploration and use by all States;”. Below this, is when airspace laws and treaties begin to apply. Over US airspace, there are laws in place to allow commercial planes, and such from other countries to fly over. But for things like spy balloons, not so. It is considered invading sovereign airspace, and a violation of international law.