The nuclear-powered guided missile sub USS Michigan is scheduled to make another port call in South Korea this weekend in what observers say is a clear warning to North Korean leader Kim Jong-un.

The sub is one of four Ohio-class boats that were converted from nuclear-missile boomers to Tomahawk platforms; each sub has 154 Tomahawks on board that can be rained down on multiple enemy targets.

The Michigan last visited the South Korean port of Busan in late April of this year, at which time North Korean state media reportedly warned “the USS Michigan won’t even be able to rise to the surface when it will meet a miserable end and turn into an underwater ghost.”

In addition to stepped up submarine visits, the Pentagon is applying additional pressure on Pyongyang over its continued development of nuclear weapons and ICBMs to deliver them. Last weekend, a pair of B-1B Lancer bombers buzzed the peninsula in a rare night-time operation with Japanese and South Korean fighter escorts.

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