Here is an analysis piece in the Stars & Stripes about what the resignation of Defense Secretary James Mattis means for the US-ROK alliance:

Mattis didn’t mention South Korea, but his departure will deprive officials in Seoul of somebody they considered a voice of reason in the Trump administration. It also comes as the president’s surprise decision on Syria earlier this week underscored the unpredictability of U.S. foreign policy.
“It’s certainly going to cause concern, I think, in South Korea,” said Jenny Town, a Korea specialist at the Washington, D.C.-based Stimson Center. “Mattis is one of the few people they looked to for direction and reason in an administration where it has been often difficult to decipher what our policy is and where our relationship is going.”She noted that Trump has said he may be willing to pull troops out of South Korea to save money.
[Stars & Stripes]
“It’s hard to see where this goes until we have a better sense of who’s coming next, but it’s also hard to see that this move is going to improve relations both with our friends or our adversaries at this point,” Town said.
You can read more at the link, but trying to equate withdrawing troops from Syria with withdrawing USFK is quite a stretch as speculated on later in the article. The US has treaty obligations with South Korea that cannot cause a quick troops withdrawal like what is expected in Syria.
Something that could lead to a partial US troop withdrawal in South Korea it is the ongoing US-ROK cost sharing negotiations. Another possibility to save money as well as send a message to North Korea if denuclearization talks are not going well, is restricting US military dependents from South Korea:
The friction escalated in January when Trump ordered Mattis to end the practice of allowing the family members of U.S. troops stationed in South Korea to accompany them during their deployments. But Mattis, with the assistance of chief of staff John Kelly, put off implementing the directive, say one defense official and one former administration official, angering Trump.
NBC News via a reader tip
Trump repeatedly said he wanted to sign an order changing the policy on military dependents in South Korea, but Mattis and other officials, including Kelly, tried to stall him, according to three former officials. “It was kind of like a game of tag. There were plenty of other people, in addition to Mattis, who slow-walked that,” the former official said. The order was never implemented.
“He knows that he told them to do it and they didn’t do it,” another former senior White House official said.
I guess we will see how all of this plays out over the next year.









