If you speak German you might be interested in this article regarding the very similar case of the US Base Rammstein located in Germany, which is used for drone

If you speak German you might be interested in this article regarding the very similar case of the US Base Rammstein located in Germany, which is used for drone strikes in the middle east https://verfassungsblog.de/ramstein-deutschlands-mitverantwortung-fuer-voelkerrechtswidrige-drohnenangriffe/ https://verfassungsblog.de/ramstein-deutschlands-mitverantwo... It's difficult to give a complete summary but basically there already have been some judgments by courts in Germany regarding the air base. Those judgments state that there are certain obligations arising from the constitution and also from international law when it comes to supporting the US in coordinating drone strikes. Things get tricky because it's not even clear what the US army is doing exactly in Rammstein and also the German governments obligations under international law (in particular their contract with the US) have to be considered when restricting their duty not to allow targeted killings. I don't think you could argue that the current judgment "leaves a loophole" because the BVerfG might reasonably make a judgment in the future that the German government may not allow CIA monitoring in Germany. (Or it might not do this, but this judgement does not indicate anything in this regard)