During the 2022 Russian invasion of Ukraine, NATO rejected Ukrainian requests for it to institute a no-fly zone over Ukraine. Of the thirty NATO members just three, the Baltic states, have voiced support for it. A no-fly zone is a form of demilitarized zone in which a military power establishes an area over which certain aircraft are not permitted to fly. No-fly zones can include preemptive attacks to prevent potential violations, reactive force targeted at violating aircraft, or surveillance with no use of force.