You want me to think up strategies on behalf of America?
Alright, I'll bite.
Instead of constantly drawing red lines and making threats that everyone just ignores, try putting your money where your mouth is.
When you draw a red line (like the famous red line in Syria), you must uphold it. If you fail to uphold it (as with Scarborough shoal, the Ukraine, etc.) then nobody will take it seriously.
America says that North Korean nuclear weapons are unacceptable, then they must be removed. If you can't do it, then don't draw red lines in the first place.
Same with the Scarborough shoal. America should uphold their "mutual defense treaty" with the Philippines, and try to forcibly remove it from Chinese hands. Why make a promise if you have no intention of keeping it?
Donald Trump, for all his craziness, is someone who might understand that. The "global policeman's" red lines are ignored by everyone, time to fix that. Like in Poker, choose a battle you are willing to fight, and then go all the way. If you're not willing to fight a battle, don't boast and draw red lines, just fold and concentrate on the ones you can win.