if it were free for all trading may work. you would need countries to have difernt units. like and japanese fighter defending on 5 and russian fighters on a 3. then russia could be like i’ll buy a japaese fighter for m japanfor 10 ipcs. japan would (if it were to trade) buy on figther and put it on a transport or in a bomber. the transport/bomber would have to drop the fghter off somewhere in russia.