They might start with us by launching an EMP attack. EMP is the ultimate in asymmetric warfare. If they can just launch one warhead to the right altitude over the U.S. they can turn the lights out for good. I remember reading about an assessment based upon wargaming this scenario that estimated 100 million dead in the U.S. within 6 months from an EMP attack. Without electricity or electronics our society can’t function.
Hopefully Trump will replace EPA insanity with an CPA (Citizen Protection Agency). The CPA's first assignment can be assisting with the process of hardening all strategically critical chips... from Power Plants to jets to City Water Filtration Plants...