Which country was not a member of allies who fought against the central powers in ww1

the allies were Britain, France, Russia, Italy and the United States

United States was an 'associate power' and it was not an official ally but fought against the central powers in World War I

Explanation:

The allies were the countries formed by triple alliance and the United States which battled against the dominant central powers. Triple entity called triple Entente was formed which means that there was an informal indulgence among Britain, Russia and France which was formed to oppose the central powers. Japan articulated its detachment and open mindedness but later joined the allies.

Associate powers were United States but later on it joined the allies and fought against the Axis powers. Associate members included Serbia and Romania too.