Fit them with transponders and broadcast schedules well in advance of flights. The destination can veto a flight at any time before launch, and have inspectors at the point of launch. In this way, Moscow (etc) could keep arrivals down to a limit that their antiballistic defenses can handle, and ensure that only people-carriers are being put into their airspace. An attacker would be limited to a single kinetic suicide attack before their target goes on high alert.

But I was more curious about the fuel efficiency...