In 1953 the percentage of GDP from manufacturing was 28%. In 2012 it was at 12%. I'd call that a drop.
Were you really confused by this, or are you just trolling now?
In 1953 US GDP was ~$2.5 T in 2009 dollars. Today it's ~$16T in 2009 dollars.
Can you see now that US manufacturing has grown significantly? The rest of the economy just grew faster, shifting our focus over the years. Much the same happened with farming before that. Technology is neat that way.
What real threat do any of these nations pose?
Again, appearance of strength is important. People who are a threat seeing the US as weak and starting a war would be a catastrophe from any moral perspective. We do get judged, like it or not, by whether minor player can shake their fists at us without consequence. Was is a surprise to you that Russia is getting froggy again (occasionally hopping across its borders) over the past decade?
Geopolitics aside, some would say that a strong man who sees a horrific crime that he has the strength to stop has the moral responsibility to do so. ISIS has conquered territory by force of arms - do we want to allow that sort of thing to be acceptable on the world stage again? The way ISIS is treating their conquered subjects is horrific and appalling, and we should probably put a stop to it.