Chinese intervention if US forces reach China's border in Vietnam

Would China intervene if the United States pushed through North Vietnam to the Chinese border?

Probably, though North Vietnam might have serious reservations about Chinese intervention.

The Korean War provides the comparison for a likely Chinese military response to American forces approaching the border. Intervention is considered probable if the United States pushed through North Vietnam. The answer also stresses that Chinese and Vietnamese relations carried their own long history of tension. Shared opposition to the United States would not erase Hanoi's reasons to view a large Chinese presence warily.