The Germans were a unified people - the days of warring germanic tribes were long over. They were a self-sufficient country and as industrialized as anyplace else. They had just been humiliated in WW1. Their economy was artificially depressed, due to treaty terms. And a majority of Germans of the time shared a latent/active hatred of Jews (a unified people and a religion, but not a nation.) Remove one of those factors, and the Nazi party causes much damage but cannot threaten the world.

skip to today - I can't think of one country where ALL of those factors are present. I can think of any number of places where some of the factors exist. Palestine comes close, but they are nowhere near independent, and much of their population live outside of the occupied territory. As you noticed, a truce with A doesn't mean jack to C.

I've heard several Islamic authorities condemn the killing of civilians, via suicide bomb or any other method. Killing non-combatants is expressly forbidden in the Koran.

But yes, we will have to deal with these guys forever.