Hitler urged the Belgrade government to join the Tripartite Pact, and on 4 March he and Ribbentrop put heavy pressure on Prince Paul.
The Yugoslav government delayed, well aware of growing opposition within the country, but the demands from Berlin became too insistent. Finally, Prince Paul and representatives of the government signed the pact on 25 March in Vienna. Two days later, Serbian officers seized power in Belgrade. Prince Paul was removed as regent and the young King Peter II placed on the throne