I am no legal expert but from what I have learned over the years is that the country of origin pretty much keeps "control" of the weapon system. Obviously it varies with each country. It is very encompassing subject with lots of variations....
The US has a bunch of laws like ITAR, United States Munitions List (USML), Congress, state department and DOD rules, Arms Export Control Act, I think even FBI or ICE can get involved with this stuff....No joke, looking for this info, saw that some professors have been prosecuted under AECA for sharing/teaching classes and giving away IP info.....I would say that the USA keeps the right to block the resale of equipment to another country, in this example of Patriot missiles going from Germany to SKorea, I am pretty sure someone from Germany told the US that they would be transferring these missiles, even if Germany has the license, they probably would have to tell, I am guessing but generally that's how it works...maybe this was part of a previous order or Germany was authorized before to sell/transfer these missiles...maybe Germany has an authorized list from the USA of countries that they can do this with...
Also I might depend if it is an FMS sale or direct buy from OEM, maybe that might change things...If it is a licensed production, maybe it is for a set quantity with no possibility of sales/exports, maybe you only have an authorized list from USA, a regional license or worldwide license, so there are quite a few things that are allowed or not...
USA is pretty strict with this stuff, yes, Spain wanted to sell transport planes to Venezuela but US didn't authorize it. Same goes for Iran, good luck getting new Boeing's or Airbuses...European nations have gotten pretty good at removing US items from their weapon systems or other equipment like satellites parts....to avoid being constrained by ITAR...Another example is SAAB with Gripen fighter jet, USA has a say where Sweden can export that fighter because of the engine F404...
I am going on a limb here but I think UAE has a block on the AN/APG-80 AESA radar for the F16 Block 60... or maybe they own the rights to something on the Block 60, they paid for the R&D so they have the IP, not really sure what....so does that mean UAE could stop the sale of a Block60? Yes, but I am guessing here, maybe someone could clarify that one....
The latest Block 50/52 is pretty close to a Block 60 but I am not sure LMT could sell a Block 60...
Actually, the example you use with you wanting to resale your Ford and having to ask permission from Ford is quite close to what happens out there,IMHO.
Would love to here more about this stuff, with luck someone could shed some light on this subject...