Story highlights The US Navy submarine docked in the port city of Busan, South Korea

The USS Michigan is meant to send a strong message to Pyongyang

Washington (CNN) The USS Michigan -- a guided-missile submarine -- arrived in South Korea for what a US defense official described as a show of force amid tensions between the US and North Korea.

The US Navy sub arrived in the port city of Busan, South Korea, on the same day that North Korea celebrates the 85th anniversary of the founding of the Korean People's Army.

Publicly the US Naval Forces Korea called the sub's visit to the region "routine" and said the scheduled port call was a chance to highlight the alliance between the US and South Korean navies, but quietly officials told CNN that the timing is not a coincidence.

While the USS Michigan is not expected to take part in the joint exercises, its presence in the region is meant to send a strong message to Pyongyang.

US President Donald Trump told Fox Business Network's Maria Bartiromo earlier this month that the US was sending an "armada" with submarines to the region.

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