Another and more immediate concern is that anything which contains subcomponents/subsystems or parts from US origin companies runs into ITAR and MTCR [1] issues with the US federal government. There's a number of very complex European origin final aviation/aerospace industry products which are laden with US-origin components. I wonder about exactly how "non-US" this Isar rocket is.
I would put it as a much greater likelihood that the US would decide to mess with export-control permits for various subsystems than a theoretical scenario where they begin intercepting western European flagged cargo ships on the way from Europe to French Guiana.
[1]: https://en.wikipedia.org/wiki/Missile_Technology_Control_Reg...
I would put it as a much greater likelihood that the US would decide to mess with export-control permits for various subsystems than a theoretical scenario where they begin intercepting western European flagged cargo ships on the way from Europe to French Guiana.