I've always questioned this. Who made it OK for the US to have bases and build ups in other countries, but other countries cannot do the same? Like when Russia and Cuba had a deal, we almost went to war over it. But yet at the time, the US has missiles located close enough to Russia.
I began to question this when I was in high school with the N.Korea nuke thing. It really should not be our business what other countries do, unless we are the official world police. Like not OK for N. Korea, but OK for China, Russia, Japan, etc...