One of the most common types of AK rifle in existence today is the Chinese Type 56 in its several variations, although very few of those rifles are in the United States in authentic full-auto form. This particular one was captured by a US soldier in the Vietnam War, who brought it back and registered it, making it a fully transferrable gun.
The Chinese received the technical package for the AK (and also the SKS, among other weapons) from the Soviet Union in the 1950s, as part of the USSR’s policy of providing military and technical aid to other nations sympathetic to the Communist cause (although a rift would grow between the USSR and China later). China would manufacture tens of millions of AK rifles, both of this milled receiver type (the Type 3 style) and the later stamped AKM pattern. The standard fixed-stock rifles like this one were fitted with under-folding spike bayonets. Folding stocked types were also made, both underfolding (Type 56-1) and side folding (Type 56-2). These weapons have become extremely prolific, and can be found in virtually any significant international conflict zone to this day.