Americas death knell as world police force?

No, I’m not America bashing…for once. After watching the news and hearing nothing but more trouble in Iraq I just got the question stuck in my head, is America finished as a world power?
When a supposed ‘Super-power’ can’t even take control of a nation such as Iraq, what hope have they of defeating a large nation such as China or Russia?
Maybe I’m jumping to the wrong conclusion but it looks like Americas days as the worlds bully boy are numbered.
Thank God 😀