Trump's Iran war is not S. Korea's war

South Korea faces an uncomfortable question: How much should an ally sacrifice for a war it did not choose?

U.S. President Donald Trump increasingly appears to expect Seoul to answer: more.

As the U.S. war with Iran enters its seventh month, Washington is pressing Seoul to contribute to efforts to secure the Strait of Hormuz. Seoul has sent an inspection team to the United Arab Emirates and is considering possible contributions to maritime security, but says no decision has been made to deploy troops. Any military deployment would require parliamentary approval.

South Korea has legitimate reasons to care deeply about Hormuz. The strait is critical to its energy security, and disruptions have contributed to rising oil prices. Brent crude recently climbed above $107 a barrel as fighting and attacks on regional energy infrastructure intensified.

But an economic interest in keeping the waterway open is not the same as an obligation to join a U.S. war.

That distinction has been blurred by Trump’s increasingly unilateral approach to alliances.

The most troubling aspect of Washington’s pressure on Seoul is not that a U.S. president is asking an ally for assistance. Allies ask one another for help during crises. The problem is the apparent assumption that refusing can carry a price.

In August, Trump ordered a reduction in major South Korea-U.S. military exercises, explicitly linking the decision to Seoul’s reluctance to assist Washington's war effort against Iran. The move alarmed officials and analysts because those drills are not simply diplomatic favors to the U.S.; they are central to deterrence against North Korea.

The message is difficult to miss: cooperate with Washington’s war, or risk paying a price for the alliance.

That is not how a durable alliance should work.

South Korea has stood beside the United States for more than seven decades. American forces remain stationed on the peninsula, while South Korea maintains a sophisticated military and bears substantial costs for the alliance. The purpose of this partnership is to deter North Korean aggression — not to give Washington leverage whenever it wants Seoul to participate in conflicts elsewhere.

The timing is particularly troubling. North Korea remains a nuclear-armed state and continues to develop missiles and other military capabilities. Pyongyang has already seized on the reduction in U.S.-South Korean exercises, while regional officials warn that weakening the alliance could create opportunities for North Korea and China.

Washington should therefore ask whether its pressure on Seoul is strengthening the alliance or consuming its strategic capital.

There is also a fundamental question about the legitimacy of the war itself.

Trump launched major military operations against Iran on Feb. 28 without first obtaining specific congressional authorization for war. His administration has offered its own interpretation of the War Powers Resolution, arguing that subsequent developments and a temporary ceasefire affected the statutory timeline. But legal scholars have challenged that reasoning, while Congress has repeatedly sought to assert its constitutional authority over the use of force.

That matters to South Korea.

A U.S. president who has not secured congressional authorization for an open-ended war has limited moral and political grounds for demanding that another democracy send its soldiers into the conflict. Seoul’s decision should not be made simply because the U.S. leader wants greater allied participation.

Nor is this merely a constitutional dispute. The war is becoming increasingly difficult to define and end. Trump has suggested that the United States might remain in Iran and benefit from its oil, while indicating that the conflict could continue until later this year.

That is very different from a limited military operation with a clearly defined objective.

South Korea should be particularly cautious about entering a conflict whose end state Washington itself has not clearly articulated.

There are, however, ways for Seoul to protect its interests without becoming a combatant. It can support freedom of navigation, provide maritime information, protect Korean commercial shipping and cooperate with international efforts to keep the sea lanes open. Seoul can also work with European and other partners on a multilateral framework rather than simply responding to demands from Washington.

That would demonstrate alliance solidarity without requiring automatic military alignment.

The risks are real. Iran has warned that South Korean military participation in the Gulf would carry consequences. Seoul would therefore be assuming potential risks to its personnel, ships, businesses and diplomatic interests. South Korean public opinion also deserves consideration. A government cannot casually send troops into a distant war when its citizens are divided over whether such a deployment serves the national interest.

Trump’s approach risks turning a difficult strategic calculation into a loyalty test.

That would be a mistake.

America needs South Korea to remain a reliable partner on the Korean Peninsula. Seoul needs the United States to remain a credible deterrent against North Korea. Both countries therefore have a profound interest in preserving the alliance beyond the tenure of any one president.

An alliance is not a protection racket. Nor is it a subscription service in which benefits can be withdrawn whenever one partner refuses an unrelated demand.

South Korea should stand with the U.S. when its own security interests and international responsibilities justify doing so. But it should not send its soldiers into Iran merely to demonstrate loyalty to a U.S. president.

The better course is principled cooperation: protect freedom of navigation, defend Korean economic interests and coordinate closely with Washington — but insist that any military deployment be based on South Korea’s own national interests, domestic law and democratic consent.

Trump may regard that caution as insufficiently loyal. In fact, it is what a mature ally should do.

The U.S. did not build its alliances through presidential demands alone. It built them through treaties, institutions, consultation and mutual confidence. If Trump wants South Korea to share the U.S.’ burdens, Washington must first demonstrate that it is prepared to share decisions with its allies. Otherwise, the greatest casualty of the Iran war may not be another ship in the Gulf. It may be trust in the alliance itself.

Shim Jae-yun is chief editorial writer of The Korea Times.