So, unless the US is faced with imminent invasion, they should stick their heads in the sand?
China is in the process of forcibly taking over an enormous chunk of geography in the south china sea. They have fired on and intimidated their neighbors such as Vietnam and Philippines in connection with this. They continue to undermine and isolate Taiwan. They are a big part of why N Korea has nuclear weapons and ICBMs.
Russia is illegally occupying a big chunk of Ukraine, is involved in shooting down civilian airliners, and assassinating people they don't like with chemical weapons.
At what point would it be advisable to see a trend and try to do something about it?