That is a very good question. it is an interesting fiction scenario to consider. Without lend-lease the Soviet Union would have lost the eastern front of the war, and perhaps the western allied forces too on the west. That would be a result of a quick victory of operation Barbarossa in Russia; the Nazi army wouldn’t have needed the solders and material it did to keep fighting the Red Army reinforced with British and American equipment.
In just part of 1941 the Soviets lost more than 20,000 tanks leaving fewer than 700 to defend Moscow. Britain provided lots of tanks and other supplies then before the U.S.A. got fully ramped up to send material.
For the Battle of Moscow the allies had sent 700 aircraft to the Reds. By the middle of 1942 they had sent appx 2000 tanks. Other stuff like metal cutting equip probably helped.
Soviet General Zhukov said after the war; “"Now they say that the allies never helped us, but it can't be denied that the Americans gave us so many goods without which we wouldn't have been able to form our reserves and continue the war,"
"We didn’t have explosives, gunpowder. We didn’t have anything to charge our rifle cartridges with. The Americans really saved us with their gunpowder and explosives. And how much sheet steel they gave us! How could we have produced our tanks without American steel? But now they make it seem as if we had an abundance of all that. Without American trucks we wouldn’t have had anything to pull our artillery with."
The Soviet Communists dominated Russia, and their power in Eastern Europe lasted a half century; a reasonable amount of time for any nation that has lost 20–30 million dead to foreign invaders to occupy lands invaded by their enemy to assure that the danger is past. If it was the United States they probably would have kept the land for a century before thinking about letting go.
One would have had to realistically consider the Nazis dominating Russia and liquidating more inferior people; not just profiled democrats, but oddball liberals of all kinds. The Soviets absorbed punishment and casualties from the Werhmacht yet caused a lot of German casualties in defense. It is possible that without the Soviets fighting on the Eastern front the Nazi might have won on the western front.
A quote from the webpage above; “More than 14,000 U.S. airplanes, 8,000 of which came from Alaska, were given to the Soviet Union in the course of the war.
The USSR received a total of 44,000 American jeeps, 375,883 cargo trucks, 8,071 tractors and 12,700 tanks. Additionally, 1,541,590 blankets, 331,066 liters of alcohol, 15,417,000 pairs of army boots, 106,893 tons of cotton, 2,670,000 tons of petroleum products and 4,478,000 tons of food supplies made their way into the Soviet Union.”
The better way to prevent communism in Russia was in World War I; if the United States had not fought against the Germans then, or if Germany were doing well in the war, Germany might not have sent Lenin to guide the revolution. Why they did isn’t too mysterious; they didn’t trust the tsar not to repeat a war on Germany (my guess), and Lenin arranged to give the Ukraine to Germany in exchange for German help in getting the revolution (the sealed train) going and peace. If Germany were winners in the first war Hitler wouldn’t have risen to power and the Nazis would not have existed. German hegemony over Russia would have created a different, though not perhaps a better political world.
