Slightly more devious question. How many weapons and systems are sold where the customer has a 100% guarantee (and a way of assuring themselves that it’s true) that it’s not a watered down spec, or that the supplier (whether industry or state) may make details of the system available to others - either in a wartime assistance sense or as a precursor to further sales? Or that something critical wouldn’t be withheld (support, spares, crypto etc) in certain circumstances? Whether or not such dastardly practices are widespread it would be an optimistic customer who assumed that they weren’t.
Prime example - Blue Fox radar (Sea Harrier FRS1), as sold to India. We didn't allow them the mid-life upgrade, which was essentially a technology demonstrator for Blue Vixen (FRS2/FA2) and EFA ECR90. The fact that some kit was handed over to India accidentally by the sailing Navy is a different matter. They didn't know what it was and returned it.
Westinghouse - RN and RAF were within days of having to ground the SAR fleets in 1989, as Westinghouse pulled the plug on support at the last minute, having accepted a contract 18 months before. Luckily, the Design Authority (MEL) sales manager found supplies in a back street shop in Lagos. Inserted in little black book, and never engaged again while I managed fire control and surveillance radars. A very rare occurrence I might add.