The mess the US foreign policy of the previous administration caused in Middle East alone ( not counting Ukraine and Libya ) has an immense cost and no real benefit. Of course others are left alone to pay the bill.
I would call that a total failure by any possible interpretation.
You can only call that a total failure if you ignore the entirety of human history and compare it to some fantasy of world peace instead. It's good to thrive for a better world, and notice when things go worse, but when evaluating effectiveness of american military as a whole, you should compare it to a time before Pax Americana.
Also, did I understand you correctly: you not only want to cut american military spending, but also keep US morally responsible for situation in Ukraine?... Now, both these viewpoints are to some extent reasonable, if they come from corresponding first principles. But I can't possibly imagine how the same person can hold these two views at the same time: they completely contradict each other. Either US is responsible for events across the globe, OR it shouldn't have a huge military - how on Earth can you believe both?!
What is the US supposed to do? You literally cited two cases, Ukraine and Libya, which are polar opposites. Ukraine the US is criticized for NOT intervening, middle east and Libya US is criticized FOR intervening.
And now we have Myanmar muslim situation and Yemen where people are begging for US intervention, but in all probability if we intervened we would be getting criticized for it by the same people asking us to intervene in a few years
>and US and their trade partners enjoy safe trade routes
Bingo, and that's from the Navy and the U.S. Coast Guard actively patrolling GLOBAL waters.
Maritime piracy alone is a considerable economic threat, yes in the 21st century. An estimated 2 BILLION dollars a year is spent on naval operations just off the coast of Somalia (PDF WARNING - PDF WARNING - PDF WARNING http://www.ics-shipping.org/docs/default-source/Piracy-Docs/... )
In this article from 2014 ( https://worldmaritimenews.com/archives/134829/annual-global-... ), again just Somalia, "The OEF estimates the total cost of piracy off the coast of Somalia at US$7–US$12 billion in 2010; US$6.6–US$6.9 billion in 2011 42 and US$5.7–US$6.1 billion in 2012".
I would call that a total failure by any possible interpretation.