July 23, 2026
SEOUL – A difference between South Korea and the United States over Seoul’s high-altitude missile defense capabilities is complicating efforts to set a target year for the transfer of wartime operational control, or OPCON.
According to multiple sources, the two sides differ over whether a timeframe for the transfer can be set without South Korea first fielding and operationally verifying the necessary high-altitude missile defense capabilities.
“The area where South Korea and the United States differ in their assessments is the South Korean military’s high-altitude defense capability,” a Defense Ministry official said, speaking on condition of anonymity.
“The US believes the capability must actually be in place and verified, while South Korea believes there is no problem with setting a target year because plans to field the capability are already underway,” the official added.
The Lee Jae Myung administration, which has made completing the OPCON transfer within its term a key policy goal, has sought to propose a specific target year — often referred to as the “X-year” among Seoul officials — by the end of this year.
Washington, however, has emphasized a strict conditions-based transfer, saying that a specific timeline should not be set until South Korea has acquired the necessary capabilities and demonstrated its ability to operate them.
The OPCON transfer has been pursued based on assessments of three conditions: the South Korean military’s ability to lead the allies’ combined defense, its capability to respond to North Korea’s nuclear and missile threats, and security conditions on the Korean Peninsula and in the region conducive to a stable transfer.
The allies, however, have not publicly disclosed which specific area has been the source of their differing assessments.
South Korea currently has no domestically operated system deployed to intercept ballistic missiles at altitudes of roughly 50 to 150 kilometers. Defense of that layer depends substantially on the Terminal High Altitude Area Defense, or THAAD, system operated by US Forces Korea.
The South Korean military completed development of its domestically built long-range surface-to-air missile system, known as L-SAM, in 2024 and began mass production last year. Operational deployment is scheduled to begin in 2027.
Officials in Seoul say the completion of development, the start of mass production and the detailed deployment schedule provide sufficient grounds to set a target year in advance.
Seoul’s position is that announcing a target year would not amount to an immediate transfer of wartime operational control, as the necessary capabilities could still be fielded and verified before the transfer actually takes place. It therefore sees no obstacle to setting a target year in advance.
Washington, by contrast, believes that completing development or beginning mass production does not in itself demonstrate that the capability has been acquired. The system must first be deployed and its operational capability verified before a target year can be set.
The difference in assessments has complicated efforts by the two sides to agree on a target year, the officials say.
The issue has also drawn attention following a controversy during the recent Middle East crisis over whether THAAD-related equipment and other US air defense assets stationed in South Korea could be moved outside the peninsula.
Meanwhile, a separate official cautioned against assuming that US concerns were simply limited to L-SAM not yet being deployed.
“The US may be assessing South Korea’s overall missile defense capability, including detection and tracking, command and control, engagement capabilities and interoperability between South Korean and US systems,” the official said.
Such upper-tier missile defense capabilities remain limited to a relatively small number of countries.
The US, Russia, China and India are among those that have independently developed and successfully tested interceptors designed to engage ballistic missiles at altitudes extending into or beyond the 50-to-150-kilometer range.
Other countries have acquired US-developed systems instead. The United Arab Emirates and Saudi Arabia operate THAAD systems purchased from the US, while Israel hosts a US-owned THAAD battery operated by American troops.