I don't think Russia and China will tolerate a U.S attack without any direct threat to its territories.
I think NK will carry on testing missiles until they get that long range ICBM. Can you really agree with saying oh well this specific country is not allowed an ICBM?
People act like Russia and China have an equivalent conventional force to America, they don't. America's military is more powerful than China and Russia's combined, and it's not even close really.