Donald Trump has claimed that South Korea would be paying over €9 billion a year for the US forces stationed on the Korean Peninsula if he were still president — triggering an alarm in Seoul as the Republican candidate seeks to return to the White House.

"If I were there now, they would be paying us $10 billion a year," Trump said about the US deployment in South Korea last week. "And you know what? They would be happy to do it. It's a money machine, South Korea."

Trump also claimed that Seoul pays nothing for what he said were 42,000 soldiers based in the South. In actuality, Seoul is currently paying around $1.02 billion per year for some 28,500 US personnel stationed on its territory. In the most recent Special Measures Agreement signed between Seoul and Washington earlier this month, Seoul agreed to boost its expenditure to around $1.09 billion per year from 2026.

Election on knife-edge

During his presidency, Trump insisted on getting South Korea to pay about $5 billion. Seoul managed to delay the discussion until late into his term, by which time it was no longer a priority.

In last week's interview at the Economic Club of Chicago, Trump also said the US "cannot be taken advantage of any longer, in trade, in the military."

With the latest polls putting Trump neck-and-neck with rival Kamala Harris in the November 5 vote, South Korean leaders are worried that its payments to Washington will take priority in his foreign policy objectives.

Trump lacking 'any idea of military strategy'

"This could have been expected, of course, because it was his previous position on US forces stationed here, although he has come up with a figure that is scandalous and without any basis in the reality of the cost of US troops in Korea," Rah Jong-yil, a former diplomat and senior South Korean intelligence officer, told DW. 

"If he is elected, then I fully expect him to demand that sort of amount from South Korea," Rah said. He added that he hopes military and diplomatic advisers in a new Trump administration might be able to explain the importance of maintaining alliances and convince the president to moderate his demands.

"I do not believe they would agree to an extortionate figure like that," Rah said. "Maybe Trump believes the military presence here is exclusively to the benefit of South Korea and that others can explain why it is important for the US, as well. I hope they can get that across because I do not think he has any idea of military strategy or international relations."

Pyongyang likely to exploit cracks between Seoul and Washington

Editorials in South Korean media have already speculated about Trump's potentially withdrawing military support while the country faces an ideological and unpredictable rival in North Korea in geographical proximity to US rivals Russia and China.

Any excessive demands from the United States could weaken the alliance and foster "anti-American sentiment among the South Korean public," according to a recent article in the Korea Times.

"This sentiment could be particularly dangerous in the current geopolitical climate, where North Korea is already ramping up military provocations. Recent actions by North Korea, such as dismantling roads leading to South Korea, signal an increasingly aggressive posture that could exploit any perceived weakness," the paper writes.

South Koreans already signaled their distrust and dislike of the Republican candidate in a July poll by the Brookings Institute, with only 12% of South Koreans saying they were in favor of Trump's occupying the White House again and 39% who preferred then-candidate and President Joe Biden.

Trump hinting at $10 billion likely a 'bluff'

Economist Park Saing-in, of Seoul National University, also expressed his disappointment with Trump and decried his "very aggressive stance he is already taking with regards to a friendly, allied country."

"From past experiences, yes, I am sure that he will try to push the South Korean government hard to pay more if he wins, but I do think he is making these demands primarily to appeal to a domestic audience in the US in the run-up to the vote," he told DW.

"As well as making Korea a campaign issue, it is also very likely that the $10 billion number is a bluff, a first negotiation with the Korean government," he said. "In truth, that figure would be impossible for the Korean government to pay, so I hope it would be seen as the starting point for negotiations."

No matter Trump's intent, Park said, the Korean people have a low opinion of him, in large part because of his "rudeness to allied countries."

US protection of South Korea 'makes strategic and economic sense'

Leif-Eric Easley, professor of international studies at Ewha Womans University in Seoul, is optimistic that the cooler heads of Trump'ss advisers would prevail should he return to the White House.

"While bluster about defense burden-sharing could damage trust between allies and embolden rivals, US troops will remain in South Korea for the foreseeable future because the current arrangement makes strategic and economic sense for both countries," Easley said, suggesting that Washington's attention might largely be focused on Ukraine and the Middle East.

The most enduring lesson of Trump's political career and his time as president, however, is to constantly expect the unexpected.

Edited by: Darko Janjevic