[kobayashi]

You had me until your last para. The sanctions against Iran were most certainly not akin to a declaration of war. If Iran had viewed it as such, it would have likely closed the Strait of Hormuz in retaliation, which it regularly vows to do if a warring scenario were to arise. So not even Iran viewed the sanctions as war-like.

The sanctions were are digression from international norms meant to coerce an equally disruptive violation of international laws - the covert production of highly enriched uranium and the illegal development of nuclear weapons.

The implementation of trade restrictions on Chinese goods would probably start a trade war, and another Cold War seems to me to be a plausible outcome. I agree with your conclusion on that point.