Belarus forced down an airliner crossing its airspace in order to arrest a passenger — Roman Protasevich, a Belarusiano protest organizer who had gone into exile.

Lukashenko's toadies say they will kill him.

How to push back? Other countries could close their airspace to flights going to or from Belarus airspace, until Lukashenko frees Protasevich and commits not to do this again.

In spirit, this resembles what the UK did to David Miranda when he transited through the UK with a copy of Snowden material. However, that did not involve forcing down an airliner.