The “kill switch” is the logistics pipeline.
Look at Iran and their purchase and use of F-14s that we sold them before friendship ended. We (arguably) prematurely halted development and use of that airframe, and destroyed the aircraft when they were decommissioned instead of mothballing them, so that they would not be able to be used at spare parts. That’s the example case to compare against here. Granted, the situation and specifics are different, but there are still enough similarities to be a valid comparison point .