Balderdash. The US saved the world, obviously, with weapon, aircraft, and ammo production for itself and its allies; singlehandedly snuffed the Japanese navy, which is more than the UK was able or willing to do; and built the landing craft for the invasions of Winston’s “soft underbelly of Europe” and D-Day. The UK sat back and waited while Germany expended itself in the Soviet Union. Speaking of the USSR, Stalin did more to save the world from the Nazis than did Winston Churchill.
90% of the German soldiers killed in WWII were killed by the Red Army.