US President Donald Trump has won adulation among supporters and notoriety among opponents for weaponizing trade. Now, in what may prove a similarly contentious move, he appears to be monetizing defense.

Using his preferred form of communication, Twitter, Trump wrote on Wednesday that South Korea “… now feels an obligation to contribute to the military defense provided by the United States of America.” In fact, South Korea has, since 1991, paid a percentage of the costs of stationing US troops in their country, suggesting that what Trump – who is prone to typos – was referring to was an increase in the South Korean contribution.

His tweets continued: “South Korea has agreed to pay substantially more money to the United States in order to defend itself from North Korea. Over the past many decades, the U.S. has been paid very little by South Korea, but last year, at the request of President Trump, South Korea paid $990,000,000.”

Show me the money

In February, Seoul agreed to pay 1.04 trillion won (US$879 million) in defense cost-sharing this year – an increase of 8.2% from the 960 billion won paid last year.

Even so, that is less than half the annual cost incurred by US Forces Korea, or USFK. According to US military newspaper Stars and Stripes, citing USFK documents, last year’s South Korean contribution amounted to 41% of the command’s total annual costs.

Trump also said that talks on defense costs were underway – a statement Seoul politely refuted, via a discreet Foreign Ministry statement that was texted to foreign reporters. The text noted that the 11th “Special Measure Agreement”  (SMA) negotiations – the official name for defense cost-sharing talks – had not yet started.

However, newly-minted US Defense Secretary Mark Esper is expected to arrive in Seoul late Thursday. It is not known if he will join working-level officials to kick off SMA talks. He is, however, highly likely to visit US troops engaged in low-key, joint summer drills with their South Korean allies.

Though many consider Trump an unconventional US president, the former businessman has been consistent on this issue. Since his early days in politics, he has claimed that the US has shouldered the lion’s share of defense costs, and demanded allies both east and west pay more.

Trump’s florid approach to defense diplomacy has caused some strains – not only with NATO allies, but also, reportedly, with former Secretary of Defense James Mattis.

His focus on finance has also generated  friction in Asia. Last year, South Korea-US SMA talks ran over schedule by six weeks, with the negotiating teams hitting multiple deadlocks.

Moreover, while SMA agreements usually hold for five years, last year’s only had a one-year time frame, suggesting the urgency of resuming talks soon.

The US president would appear to hold the trump card – particularly this year.

Seoul only has one military alliance – with Washington – but is surrounded by more powerful neighbors. In recent weeks, Chinese and Russian planes have probed Korean skies in their first joint exercise in the region, North Korea has test-fired a barrage of short-range missiles and in a trade spat with Tokyo, Seoul has failed to garner international support.

Alliance issues

The US bases about 28,500 troops in South Korea and also maintains the ally under its wider regional defense aegis and “nuclear umbrella.” This means that, under the latter arrangement, US troops and assets – from infantry brigade command groups to aircraft carriers to stealth bombers – frequently rotate, for short periods, into and around South Korea.

These rotations and visits are customary during periods of tension with North Korea, but also take place during joint exercises. Trump, during his first summit with Kim Jong Un last year, criticized the biggest drills, held in Spring, on the grounds of expense.

Pyongyang has consistently argued that drills, particularly annual spring war games, are preparations for an invasion.

US Forces Korea is now in the final stages of abandoning its base at Yongsan in Seoul – a location that, sitting on acres of prime downtown real estate, has been considered intrusive.

The bulk of US forces in the country have re-deployed south, to the sprawling Camp Humphreys – reputedly the largest US military base outside the United States – near the port town of Pyeongtaek.

Last year, USFK Commander in Chief General Vincent Brooks told foreign reporters that the largely Korean-funded base was “a great gift” from South Korea to the United States.

Above and beyond cost-sharing, another long-term issue overhangs the alliance: There is still no clear shape apparent for the politically charged transfer of South Korean forces from US to South Korean control in wartime. The process has been delayed for years. Set in motion in 2006, it was expected to be completed in 2012, but there is still no timetable for the transfer to take place.