 According to Chen Jian, during the mid-to-late 1960s, Lê Duẩn permitted 320,000 Chinese volunteers into North Vietnam to help build infrastructure for the country, thereby freeing a similar number of PAVN personnel to go south.There are no sources from Vietnam, the United States, or the Soviet Union that confirm the number of Chinese troops stationed in North Vietnam.However, the Chinese government later admitted to sending 320,000 Chinese soldiers to Vietnam during the 1960s and spent over $20 billion to support Hanoi's regular North Vietnamese Army and Việt Cộng guerrilla units.