The question we want to answer about this sterilization is why? The break up of Yugoslavia and ensuing conflict, very similar to today’s conflict in Syria saw an enormous diversity in the trade and manufacture of small arms, going in and going out of the conflict zones as all the various armed groups tried to get ahold of weapons to arm themselves with. Sterilization almost entirely is done to allow plausible deniability to the presence of a country’s small arms in another location. China in particular made entire batches of small arms with dedicated markings such as M21 on SKS’s, complete with actual serial numbers. These were fed into Cambodia, Vietnam, and Laos during the Vietnam War. This is a photograph I took of while in Burma of one such example-
East Germany decided to upgrade the fortifications in the late 1960s to establish a "modern frontier" that would be far more difficult to cross. Barbed-wire fences were replaced with harder-to-climb expanded metal barriers; directional anti-personnel mines and anti-vehicle ditches blocked the movement of people and vehicles; tripwires and electric signals helped guards to detect escapees; all-weather patrol roads enabled rapid access to any point along the border; and wooden guard towers were replaced with prefabricated concrete towers and observation bunkers.