They only know to act the bully, thinking this will be sufficient to intimidate the American public, oblivious to the fact that the American public is totally unaware of this blustering. What's worse is that they do not comprehend that should Americans take notice of these outbursts their reaction will be quite aggressive, the very opposite of what is hoped for. These outbursts are not emitted from a vacuum. Behind them is the very genuine worry that America will proceed with a successful national anti-missile defence system that would reduce China's nuclear arsenal to a heap of scrap. They know any attempt to breach such a system would require a continuous and horrendously expensive programme of trying to penetrate the shield, knowing that the shield itself was being continuously perfected.
China is still a very poor country.
It cannot afford the kind of 'technological arms race' that finally broke the Soviet Union. It can only hope that a carrot and stick approach will work. On the one hand, the likes Jiang Zemin will play the good cops while Sha Zukang and his ilk will play the bad cops, threatening that a missile defence system will only provoke China. Zemin will argue, however, that implementing a missile defence system will make it impossible for him to resist the military. Don't fall for it.