I have some thoughts on the diffusion of anti-access military technology over at The Diplomat
During the Cold War, the Soviet Union had a strong political incentive to maximize diffusion of its military capabilities. Proxies with Soviet technology could fight the United States and its proxies on their own. Consequently, states from North Korea to Vietnam to Cuba to Syria, Iraq, and Egypt gained access to the many of the most advanced Soviet fighter, submarine, and missile systems. Often, these systems overwhelmed the capacity of recipients, with buyers lacking the ability to put pilots in planes, sailors in subs, and mechanics in either. Nevertheless, these systems still forced the United States to act cautiously; the combination of a couple Nanuchka class missile boats, some Foxtrot subs, a few MiG-23s and a reasonably sophisticated air defense system could give the US Navy or Air Force a bad day.
Russia doesn’t see much of an upside in this kind of diffusion today. States get the equipment they can pay for, without political subsidy . China has displayed little interest in developing proxy relationships of the type seen in the Cold War. Moreover, few states have an interest in devoting resources and attention to making life difficult for a superpower. Still, given the rapidly advancing capabilities of China’s anti-access forces, questions of diffusion and proliferation bear consideration.