Under a defense cost-sharing accord with Washington, Seoul is required to pay 1.04 trillion won ($885 million) this year for the stationing of 28,500 US troops here. The amount, which represents an 8.2 percent increase from last year, marks the first time that South Korea’s payment has exceeded 1 trillion won.

South Korea is now facing US demands for a hefty rise in its contribution next year, compared with which this year’s increase would look minuscule. Washington has reportedly called on Seoul to pay $5 billion next year for the upkeep of US Forces Korea.

If so -- officials here have not denied such reports -- the US request would make South Korea go beyond sharing a fair burden and pay more than the whole cost of stationing American soldiers on its soil.

In March, the US Department of Defense disclosed the total cost for US military presence in South Korea amounted to about $4.4 billion annually.

Sources informed of the burden-sharing issue say Washington is demanding that Seoul cover the cost of holding joint military drills and deploying US strategic assets on the peninsula along with providing support for family members of US soldiers stationed here.

These requests go beyond the obligations South Korea has to shoulder under bilateral accords.

Under the Status of Forces Agreement, Seoul is obliged to provide facilities and sites to USFK, while the US is supposed to pay for all other costs for its military presence here. Under a separate Special Measures Agreement that came into force in 1991, Seoul has shouldered partial costs for local workers hired by USFK, construction work at US military bases and other logistics.

Officials from South Korea and the US are holding their second round of negotiations on next year’s burden-sharing deal in Honolulu, Hawaii, for two days through Thursday. The initial round of talks took place in Seoul last month.

It may well be that Washington’s demands that go beyond the SMA’s boundaries reflect President Donald Trump’s will to get South Korea and other US allies to pay more of their defense cost. He has openly expressed his willingness to withdraw US troops from allies whose contributions fall short of his expectations.

A statement issued by the US State Department last week noted that Trump is clear that South Korea “can and should contribute more of its fair share.” It said the US seeks a fair and equitable outcome to the SMA negotiations that will strengthen and sustain the “resilient” alliance.

But the reported US demand for a fivefold increase in Seoul’s contribution appears unreasonable. If the Trump administration had an ulterior intent to reach a deal at about half of the sum it initially requested, as some observers say, many people here would still find it excessive.

Hopefully, the US will settle for a compromise that could enable it to avoid giving the impression of being too heavy-handed with a key ally.

For its part, Seoul needs to go beyond discussions on technical issues and view the matter of defense-cost sharing from a wider perspective that takes into account the changing security conditions and possibility of Trump making impulsive decisions.

It is worrisome that the South Korea-US alliance is showing signs of weakening, with efforts to denuclearize North Korea in limbo. The two allies have felt increasingly uneasy toward each other over how to handle the North, combined defense posture following the planned transfer of wartime operational control to South Korea and Seoul’s decision to terminate a military information-sharing pact with Tokyo. They should not let a tug-of-war over the costs for the upkeep of USFK further undermine their alliance crucial to peace and stability in the region.

Seoul needs to be more flexible to hold back Trump from considering using the withdrawal of US troops as a bargaining chip in nuclear negotiations with Pyongyang. President Moon Jae-in’s administration seems to judge that it is unrealistic for the US to choose to leave, abandoning a sprawling new base in Pyeongtaek southwest of Seoul, which is set to be used for its strategy to field a global mobile force.

Trump could still opt to cut the number of USFK troops by up to 6,000, which would not require congressional approval. Even the partial pullout would leave South Korea more vulnerable to pressure from China, Russia and Japan, and could have negative effects on its economy by hurting investor confidence.