As US forces prepare to join their South Korean partners for yet another round of the military exercises that North Korean Leader Kim Jong Un is so fond of, the US has sent a nuclear-powered sub to participate.

The nuclear-powered submarine Michigan will arrive in the Korean port city of Busan, situated in the southern part of the country, by the end of the week, according to Bloomberg, which cited local media reports.

The sub will conduct joint drills with the US aircraft carrier USS Ronald Reagan in the waters off the peninsula next week.

With North Korea celebrating the founding of the country's ruling Communist Party on Oct. 10, US and South Korean defense officials are anticipating that the country could launch another provocative missile test as soon as tonight.

The US dispatched the USS Ronald Reagan to South Korea last month after North Korea twice fired IRBMs over the northern Japanese island of Hokkaido.

According to a map showing the locations of US Naval assets (the ones that've been publicly, at least) created by Stratfor, the USS Ronald Reagan is presently making a scheduled refueling stop in Hong Kong but is expected to return to the peninsula shortly.

The escalation - which conjures up memories of the time Trump revealed that he'd ordered three nuclear subs to Korea, only for it to be revealed that they were actually traveling in the opposite direction - comes as the president has stepped up his rhetoric against the North, recently offering a string of cryptic threats about a coming "storm", though he has so far refused to elaborate.

Earlier Monday, Defense Secretary James Mattis said that while the US is trying to force North Korea to halt its nuclear weapons program through diplomacy and economic pressure, soldiers must be prepared to fight if negotiations fail and things go south, Trump seems to have suggested they will.