Back in the early 1970s it was reported that the US government was making 7.62X39 unmarked ammo for someone.
The report claimed that it was still tracable to the US because they were loaded with Boxer primers when most of the world used Berden primers.
That was a period of global upheaval. Aside from the Cold War the U.S., the Soviets and the Chinese fought proxy wars with each other for control of the Third World. For plausible deniability the U.S. might disguise its support for an insurgency or counterinsurgency by supplying Eastern Bloc arms to its clients. This wouldn't fool anybody for long except for the news media. After Sadat broke away from the Soviets and allied with the U.S. Egypt delivered various Russian small arms to the U.S. These found there way to the mujaheddin fighting the Russians in Afghanistan. After Sadat's assassination there was a theory that the KGB plotted his death in retaliation.