The plasma in nuclear fusion is kept at high temperatures and when temperatures drop, the system immediately stops which means that the nuclear fusion reactions are safer.
The US and China are trapped in what Graham Allison has termed as Thucydides' trap. Under President Xi, China has taken several steps that are intended to counter US influence and liberal order.
Countries developed a taboo against the use of nuclear weapons, coming to understand them as so horrific as to be essentially unusable except in the most extreme cases of last resort. But recent events.