If you look at an obscure fact of WW2 history; you'll find out that the Japanese Government hired Seiko Fujita to train espionage agents, ingun & Japanese Naval Commandos in many aspects of ninjutsu; stealth, meditation, depersonalization and such was a large portion of this. Such organizations trained guerrillas in China & Burma which applied such derived techniques. I'm not saying they were all "ninja warriors" but that there is a reaccuring theme in Eastern & Western Guerrilla Tactics which draws historically as begun in the Middle East and moved outward (the oldest case being from the Old Testament Bible). A rare exception to this rule is the American Indian Fighters; were reputed to have the same "Mystical Ninja Skills" all derived from Native American Culture. While it seems thay human nature is abound with such examples and philosophies (A common pop-culture image being the ninja).

 

As someone who was Infantry & who supplimented my Infantry training with some individual self-styled training drawing from eastern infantry manuals. Well their camouflage and individual movement is far better then our own. I've implimented some of those tactics while playing OpFor and had great success. In actual combat I don't know...

 

I found Tigers Way & Night Movements at the Liberary on post and own both now, bought them off Amazon...