From the Russian Revolution in 1917 to the dissolution of the Soviet Union in 1991, communism had one of the largest, most robust bases-of-operation imaginable. For 45 years after the end of WW-II, 'the West' (primarily The United States) engaged in a Cold War — mostly political maneuvering, espionage, sabotage, and outright bribery — in an effort to contain the growth of the other. The most newsworthy incident of the time involved the Soviet gambit to install missiles in Cuba.
During the 80s, Ronald Reagan proposed, and the US spent time, effort, and money developing a futuristic anti-missile defense (dubbed "Star Wars" for its planned use of directed-energy weaponry). Although it never actually materialized, the Soviets had to counter the impending threat (the inventive Americanskis, after all, might actually have pulled that rabbit out of their hat) and the colossal cost of doing so bankrupted, for all intents and purposes, the entire Soviet operation. Within a few years, the Soviet Union collapsed, having run out of money. It is said in retrospect that Reagan raised the stakes so high the Soviets couldn't call the bet. It's probably an accurate description of what happened, but it raises additional questions about how the whole Cold War was waged.
The most intriguing question, I think, is 'what would have happened had we not moved to block each and every communist gambit?'
What we know with near-certainty is that socialism/communism is at the top of its game when used as a philosophical ideal. As an economic system, it's a losing bet. You can run an economy socialistically only for so long before the internal stresses and frictions make it grind to a halt. Like physical systems, entropy will eventually catch up to it. ('Entropy' for economic systems is the resistance of individuals to the central planning inherent in all socialist economies. It takes several forms which may be described as "I should move to somewhere I'm more appreciated" or "They're not paying me enough to do this job well" or "I made my quota for the week already". Each means the economy is not running at 100%.)
If a government is very careful, the game can be played for a much longer time. Sweden and Norway are examples of this although Sweden is currently seeing cracks form in its medical delivery system stressed as it is by a huge influx of immigrants from the Middle East drawn by the promise of free stuff. If the game is played less carefully, economic entropy gets you sooner rather than later. How long? The economic resources you start with play a big part in that, to be sure. Norway has North Sea oil reserves that will allow the game to go on for quite a long time. Sweden has only those reverves built up over a long period when it was a much different sort of country, economically speaking.
When the West pushed back against communist 'aggression' here, there, and elsewhere in the world, China and Russia slowed their advances and this probably made them better able to continue. What if we had just let them run rampant? Yes, they would have gobbled up lots of territory and those conquered people would suffer under increasingly repressive central planners, but that suffering is the entropy that attacks socialist systems. Might the Soviet Union have collapsed in 1981 or even 1971 had we simply let them expand unchecked?
'But an expanding Soviet Union would be a threat to world peace,' someone objects. How? It was never a possibility that the USSR would nuke the US; never. In most years, it was the output of Kansas and Nebraska that kept the people of the USSR fed through the winter. To entertain the thought that the USSR was led by people stupid enough to destroy their own food shows an alarming inability to grasp reality.
When Eisenhower left office in 1960, he left a message for us in his farewell address. In it, he warned of "the military-industrial complex' and its ability to take over our economy and our government. We didn't listen. Since then, the Pentagon's budget has grown steadily, year after year, fueled by war after war such that today if the Pentagon were its own country it would be the seventh-largest economy in the world. Just the Pentagon. A military budget bigger than France's. Not 'bigger than France's military budget'; bigger than France's budget.
There are abroad in our country people who will earnestly assert that we need a military that large to properly defend ourselves. It's fair to ask, I think, why Great Britain doesn't need a military budget of a comparable size and why France doesn't and why Germany doesn't and why Spain doesn't and (most tellingly) why China and Russia don't. The answer, of course, is that we taxpayers of the United States foot the bill for defending not only ourselves, but dozens of other countries who spend little or nothing on their own defense. Why should they if Uncle Sugar is picking up the tab? Then, too, we regularly engage in offensive military operations, primarily in the Middle East, ostensibly to combat 'terrorism' and that doesn't come cheap. Our fighting men (and women) deserve the best of the best when it comes to armaments, and don't forget our allies. They need to be comparably equipped and we need to make that happen.
There's a vast difference in the cost of fighting a war here against an invading army as opposed to the cost of fighting a war there as an invading army. Note carefully what is happening: we are expanding the way the Soviet Union expanded and there is no one around to stop us. We will expand until, just like the Soviet Union, we go bankrupt.
Who will be "the last man standing" when that happens, I wonder?