Since the 1910s, the USA has been growing into a Great Power, which some say could challenge the British Empire. President Woodrow Wilson realized this, and was also painfully aware of the secret society that has been infiltrating the European powers. He would work to ensure that America would not fall under their influence.
In 1929, America suffered a crippling blow during the Wall Street crash, which was exacerbated by Hoover signing the Smoot-Hawley Tariff Act. Members of the secret society tried to stoke up the business plot to overthrow FDR, which failed.
America under FDR also came to the aid of China after the Philippines' territory was attacked by Japan. The Pacific War ended in the defeat of Japan, and Korea becoming independent.
When the USA tested the A-Bomb in 1949, the Union of Empires (an evolved Central Powers) tested their own nuclear device in Anatolia.
After President Petrov made the missile shield operational, the UoE got their own missile shield operational, leading to a buildup in conventional weapons, which culminated in the Global War.