MIG-29 Polish Air Force
There is an “informal” agreement within the NATO bloc not to supply certain types of military equipment to Ukraine. As the portal clarifies zeit.de , we are primarily talking about tanks and airplanes.
As an example, Poland’s refusal to supply Soviet MiG-29 fighters to Kiev is cited, as well as Germany’s delaying the issue of supplying Leopard tanks to Ukraine.
The source explained that the Alliance insists that the risk of a direct military confrontation between NATO and Russia should be minimized. In the West, they fear that Moscow may regard the supply of aircraft and tanks as participation in hostilities and take retaliatory measures.