Ancient battlefield knowledge- that probably had to be re-learned or re-discovered as hard lessons to Israeli commandos then taught to American soldiers.
Forgot to mention... Spent some time a few years ago "playing" with a guy who was an Israeli commando "back in the day". Great conversations and some great times spent getting hurt.
We spent some time working on close quarter gun/knife takeaways a few times. Went home each time with lots of bruises and sore joints (and also a bloody nose from one "oops, a little too close" move). I subsequently got to learn a gun takeaway method taught to the local SWAT/LEO guys that was remarkably similar (albeit a little less "life ending" and with the atemi at a different "place" in the sequence). And we've ended up working portions of that into our training in the dojo.
Interestingly much of it was already there, but the experience of guys who'd had to do it allowed us to "refocus" things quite a bit.
It's all good.