It would be a breach of contract which Berlin could then take to court or just refuse to participate further in that contract and future ones; so they could be cut off from further weapons sales, parts, maintenance, training or w/e else
If there is any chance you plan on buying future German supplies in the short or medium term then it could be a bad idea to breach contracts. The next German government might come in and say all is forgiven, back to business but who knows how long that will take
Yep its basically a game of Chicken as I alluded to in my last post
Its a relationship based on contracts.
Most countries with defence sectors want to sell arms, they are highly profitable and a great way of earning back a good chunk of that defence spend.
Its why western countries had to agree to stop selling to the worst countries for human rights etc, they also happened to be those most willing to spend large chunks of their GDP on arms. (Of course it just opened the door more for places like Russia...)
Which makes the whole sold weapons being passed on a game of chicken and egg. If I am buying $2Bn dollars of equipment from you every year and you know I want more, but I say I am going to supply some of my existing stocks to another country that the vast majority of the world support are you really going to go, oh breach of contrat we wont sell you any more. When some of your direct competitors are also supply weaponry to the country who needs it. When I rock up next year and some, heres my order for some more of those tanks, would you really go, nope sorry no more go to one of our competitor nations?
The swiss are also in this as well. Some of the ammunition is made in Switzerland, the famous neutrality kings. Why anyone would buy anything military from Switzerland that had a usage restriction is beyond me. They are basically guaranteed to reject any request that involved anything they make being able to be used outside their borders for an active military use (ie not training).
Its that mindset of its not really going to happen playing out over and over here, and the fact its allowed penny pinching to become a significant factor in western arms manufacturing and deals.