> I’m guessing they just don’t want to seem weak and give in.
China has significantly more discipline than the current US administration and opposite to Trump's short-term shoot-from-the-hip approach, they are likely taking a page from
Sun Tsu:
If your enemy is secure at all points, be prepared for him. If he is in superior strength, evade him. If your opponent is temperamental, seek to irritate him. Pretend to be weak, that he may grow arrogant. If he is taking his ease, give him no rest. If his forces are united, separate them. If sovereign and subject are in accord, put division between them. Attack him where he is unprepared, appear where you are not expected.