What have seen since WWII is that military attacks are extremely hard. Just about all successful missions have support of the local population in the attacked c

What have seen since WWII is that military attacks are extremely hard. Just about all successful missions have support of the local population in the attacked countries. Yes, the US can take over countries like Iraq or Afghanistan. And then what? Is there any net gain for the US? On the other hand, NATO bombings in former Yoguslavia led to a situation that is still more or less stable today. Russia quickly took over Crimea, which has strategic value and has support of the local population. But now they are stuck with a nasty and costly war in Ukraine. So it is not clear where in the world Germany would play 'empire'. I wonder to what extend an army can maintain an effective defence if there no need for any defence for many decades. Many western European countries have not been attacked since the end of WWII.