After initially declaring neutrality, on 25 March 1941, although King Peter and his advisors were opposed to Nazi Germany, the Regent, Prince Paul, under immense German pressure signed the Tripartite Pact originally signed by Germany, Italy, and Japan. Two days later, in a British-supported coup d'état opposing the Tripartite Pact, King Peter, then 17, was proclaimed of age, and the regency overthrown. Postponing Operation Barbarossa, Germany simultaneously attacked Yugoslavia and Greece. From 6 April Luftwaffe pounded Belgrade for three days and three nights, Operation Punishment. Within a week, Germany, Bulgaria, Hungary and Italy invaded Yugoslavia and the government was forced to surrender on 17 April. Yugoslavia was divided to satisfy Italian, Bulgarian, Hungarian and German demands and puppet Croat, Montenegrin and Serb states proclaimed.