It only works when one party isn't interested in starting a war in the first place.

and why on earth would China want to start a war with us? We are a huge trading partner and yes there's a lot of posturing and conflicting geo-political interests, cultural views etc but that doesn't mean that war is their goal.

Diplomacy only works when both sides are playing fair. If China is going to ban US apps unilaterally, US should reciprocate in kind.