"Every one learned that in Korea and Vietnam..."
China lost in Vietnam.
How do you define winning and losing?
China invaded Vietnam, Vietnam tried to invade China into the Yunnan province but was UNSUCCESSFUL. In other words, China was able to go into Vietnamese territory and not the other way around. In this way, China wins.
If you define victory as China having to force Vietnam out of Cambodia, then you're right, they lost. But from the casualties, both side suffered about 25k men. It's a draw.
Remember 1962? China beats India without an airforce and with much less technological weapons than what India possess at that time because Indians underestimated China and didn't think it could operate in high altitudes. In the long run China did lose in terms of international image but military wise, they did achieve their objectives.
I was actually referring to the NVA-South vietnam conflict with Russian/China on one side and America on the other side...In that fight Chinese backed the NVA and eventually drove americans out...
Then chinese fell out with the NVA too..that is a different story...
In Korea also it was the chinese army through north korean proxy that fought Americans and stalemated...