Simultaneous Demands Create Strategic Dilemma
Earlier this month, President Donald Trump shared a Washington Post opinion piece on his social media platform arguing that South Korea should send its Cheongung-II air-defense system to Ukraine. In addition to the request for military hardware, the Trump administration continues to pressure Seoul to send troops to the Strait of Hormuz.
Neither the U.S.-Iranian conflict nor the Russo-Ukrainian War is new, yet the simultaneity of U.S. pressure on Seoul to help in its war with Iran and to support Ukraine is striking. According to a commentary published by War on the Rocks, such diverging asks are unprecedented, partly due to a lack of principles that stipulate a clear South Korean position.
Seoul and Tehran have cultural ties dating to a 1969 Treaty of Friendship and a 1977 street-naming exchange, with economic ties that once sent more than 200,000 South Koreans to work in Iran’s infrastructure sector. As recently as 2017, Iran supplied 13.2 percent of South Korea’s oil imports.
From 2018 until 2023, South Korea held roughly $6 billion in frozen Iranian oil revenue, released only as part of a separate U.S.-Iranian prisoner swap. China buys as much as 90 percent of Iran’s oil exports and is South Korea’s largest trading partner; Seoul cannot ignore China’s history of economic retaliation in response to Seoul’s deployment of Terminal High Altitude Area Defense.
Historical Precedents and Current Constraints
South Korea has a record of past deployments that reflects a mixture of alliance assistance, non-combat roles when possible, and adherence to the National Assembly’s consent requirement. Seoul sent roughly 320,000 troops to Vietnam at the request of the United States and deployed the Zaytun Division to Iraq from 2004 to 2008 as the third-largest contingent.
More recent operations include maintaining the Akh unit in the Emirates, Dongmyeong with the U.N. force in Lebanon, and Hanbit in South Sudan. These historical examples provide a framework for how Seoul might approach current requests, yet the political landscape has shifted significantly.
Governing Principles Under Scrutiny
Experts argue that South Korea should establish a principle requiring multilateral legitimacy before deploying troops overseas and build a Lend-Lease-style legal framework for arms sales to partners like Ukraine. Without such frameworks, the government faces legislative hurdles.
A National Assembly member notes they may soon be asked to vote on a Hormuz deployment without settled governing principles. This legislative uncertainty is compounded by the timing of the current diplomatic pressures.
Geopolitical Risks and Diplomatic Fallout
Seoul must navigate complex relationships with other global powers while considering U.S. requests. Russia has issued a comparable warning directly to Seoul, threatening “retaliatory measures, including ‘asymmetric’ ones” when Seoul considered joining a NATO-led initiative to help purchase U.S. weapons for Ukraine.
The Defense Ministry confirmed it has sent a survey team to the Strait to assess conditions. However, critics suggest that Seoul is having a premature public discussion of troop deployment only a few weeks after its annual joint military exercise with the United States was abruptly canceled and downsized.