The misconception that only America has advanced technology, especially weapons has cost many lives.
Many American weapons are stolen and/or trafficked. In some case a military shipment is hijacked, in others some ‘ally’ of America received the weapons as part of an ‘aid’ packet, but sells them to fill their right pocket.
Of course, in some cases, Russian weapons are better, so getting rid of a stock of U.S. M-16 for AK-47s is not unusual.
Further, nations can buy American or Russian weapons, pull them apart, rebuild them according to their own scheme. To be blunt; how difficult is it for a factory in Istanbul to take a legal U.S. rifle, dismantle it, copy every feature and create their own?
Further, most nations aren’t looking for World Domination, they are looking to control a specific area or destroy a specific group. The Mexican Cartels are interested in selling their drugs, not ruling Texas.