Communist Military Strength vs Capitalist Military Strength

I always see people
posting pictures of North Korea and South Korea from space and claim this as irrefutable proof of Capitalism's superiority to Communism. What they seem to intentionally cut out from the picture however is Communist China just above North Korea, which is lit up rather well from space. This is not the point of the thread however, but this is what got me thinking about what your guys opinion on this is. If Capitalism is so VASTLY superior to Communism, especially in regards to North Korea vs South Korea, then why did America and other Capitalist nations have to step in to defend South Korea from North Korea? Surely since South Korea is Capitalist and North Korea is so underdeveloped because of Communism the South should have been able to beat the North with their hands tied behind their backs? Why did they need the rest of the worlds support?

What about Vietnam? Surely the vastly superior South of Vietnam could have easily destroyer the North without our help? Im very curious what your guys excuse will be.

https://www.google.com/search?q=nor...AUICigB&biw=1920&bih=900#imgrc=O2Xg5l6s1q9SgM: