Back in the late 70s I had an A/D with a Nazi manufactured P38 (9mm). Tripped the slide release with the safety on and the weapon discharged without pulling the trigger. Fortunately I was checking one of my reloads for fit and it was the only round in the weapon. It was unnerving, but no damage done. Found out later that many P38s manufactured late in World War II were built by forced Polish labor. The firing pins were manufactured too long specifically to cause such a malfunction, revenge for being forced to work for the Nazis.
Had a Sgt in the USAF that had been on a base in England during WW II when a bomber dropped a load of bombs on their huts, the bombs didn't go off or he wouldn't of been around to tell the story. Some French or Polish forced labor had machined the fuses so they wouldn't operate or so the bomb squad that defused the bombs told them and also told them to keep their mouths shut so they could keep on doing it. Looks like from the way the poster is worded, that we can continue to use our ISIS posters for authorized targets.