U.S. Defense Secretary James Mattis was in Seoul on Thursday and Friday to meet with National Security Adviser Kim Kwan-jin and Defense Minister Han Min-koo. It is rare for a newly-appointed U.S. defense secretary to choose South Korea as the destination of his first overseas visit.

Mattis apparently chose South Korea to assess the ability of U.S. troops to thwart a North Korean provocation and to inspect the readiness levels of South Korean and American forces. The Trump administration is concerned that North Korea could resort to a major provocation as seen in 2009, when the Obama administration was launched. Mattis warned in no uncertain terms of an "overwhelming response" if that happens. In 2009, North Korea abducted two U.S. journalists, tested a long-range missile and conducted a nuclear test.

The new U.S. administration is looking for a different approach to North Korea from the Obama administration. A military option may well be among those choices given the belligerent tones emerging from Trump’s team. In Senate Foreign Affairs Committee hearings held just after Trump took office, senators called for "overturning" the North Korean regime and asked whether it would be wise to assassinate North Korean leader Kim Jong-un.

The U.S. is sure to be monitoring the political situation in Seoul as President Park Geun-hye faces impeachment. One serious uncertainty is where the next president here will stand on the deployment of a THAAD missile defense battery here.

Former U.S. assistant secretary of defense Elaine Bunn was quoted as saying Washington needs to reassess the priorities of its allies and what its allies intend to do. And Mattis told reporters before arriving here that THAAD is purely a defensive system aimed at thwarting a North Korean provocation.

Seoul and Washington are scheduled to hold talks next year on sharing the costs of maintaining U.S. troops on the Korean Peninsula. Trump has said several times during his campaign that South Korea is paying too little, but Mark Lippert, the outgoing ambassador, pointed out that South Korea covers 96 percent of the cost of building a new American military base in Pyeongtaek south of Seoul.

Both Seoul and Washington must avoid letting money problems overshadow the alliance. Fortunately, Trump has been avoiding prickly issues with Seoul so far. Wisdom and practicality must be observed by both sides at this important time.

