Defense Secretary Mark Esper speaks at a joint press conference after the 51st Security Consultative Meeting (SCM) with South Korean Defence Minister Jeong Kyeong-doo at the Defence Ministry in Seoul on November 15, 2019.

It turns out President Donald Trump's long-running demand that NATO countries pay more for their own defense isn't just about Europe. Now, the administration is stepping up its efforts to get Asian countries to cough up more too.

The specific Asian country in the spotlight is South Korea. U.S. Defense Secretary Mark Esper used his current trip there to pressure Seoul into paying more for the massive U.S. military presence there. According to one South Korean lawmaker Esper wants much more, as in five times more or $5 billion annually.

That sounds like a big mark-up. But let's face it, defending the free world isn't cheap. A big reason why is the countries that aren't part of the free world, like China, are spending record amounts on defense as well.

Demanding that Seoul pay more is basically the only option the U.S. has now. That's because the idea of closing American bases in South Korea or pulling out the 28,500 U.S. troops there is unthinkable in the face of the constant nuclear and conventional military threats from North Korea.

But cutting the number of U.S. bases isn't, or shouldn't be such a controversial idea in many other parts of the world. The U.S. currently has about 800 military bases in more than 70 countries. That number includes 174 bases and other military installations in Germany alone. We even have one in Aruba.

Each one of these foreign bases costs the taxpayers not just in maintenance bills, but in payments we often must make to those foreign countries to use their land or coastlines. There are also the costs of maintaining diplomatic relationships with those nations to make sure they don't suddenly kick our troops and bases out. At last count, the cost of maintaining those bases is $156 billion per year.