Have international mercenaries fought with China special forces?

It was played in TV series, but not in reality. Because in the present form of China, it is difficult for mercenaries to penetrate into China, both in terms of personnel and weapons.

Mercenaries are special arms that fight for money. From the barbarians in the ancient Roman army to the European prisoners exiled to Africa in the post-colonial period, mercenaries have always been regarded as a group of thugs who want money and are desperate. In many people's understanding, mercenaries bring only death and pain to others, and their only motivation for fighting is money.