South Korea has been keeping some missiles for the US, and now the US is retrieving them. The US has always found it handy to have South Korea as a custodian of its war assets, because the neighboring North Korea is always a threat.
This arrangement has also given South Korea a good level of security over the years, because it is very convenient to launch a counter-attack against North Korea if need be.
The US, South Korea, and many other countries have always considered the North Korean government rogue. This is because the country is prone to testing its nuclear missiles randomly, threatening the security of its neighbors.
Koreans Protested
As the US military trucks moved out of Seongju, where the US keeps its missile defense system, locals protested. They considered the US to be leaving them exposed to attacks from North Korea.
The war assets the US retrieved from South Korea this week are meant for deployment to the Middle East, where the US/Israel-Iran war is raging. They are missile and drone interceptors called Terminal High Altitude Area Defense or THAAD, which the US took to South Korea in 2017.
US is Straining
Many people have said that Trump acted on impulse in starting the war with Iran, and that position is gaining currency by the day.
For the US to remove from South Korea the interceptors that are meant to detect, locate, and neutralize any missiles from North Korea, it means the country is strained for appropriate war resources. This position is rendered weighty considering there are over 28,000 American troops stationed in South Korea, and they, too, will remain exposed.
Meanwhile, Japan is bracing itself for a similar redeployment of US assets in the country. If such a deployment takes place, it should be a significant change for Japan, as it hosts several naval, marine, and air bases for the US, whose support staff exceeds 60,000.