In their joint news conference after security talks here early this month, South Korean and U.S. defense chiefs avoided directly mentioning a possible connection between South Korea’s participation in the U.S.-led global missile defense scheme and a delay in the transfer of wartime operational control to Seoul.

At the time, U.S. Defense Secretary Chuck Hagel emphasized the need to bolster interoperability of the allies’ missile defense systems to counter threats from North Korea, while agreeing to continue consultations on rescheduling OPCON transition. In the lead-up to the annual Security Consultative Meeting, Hagel and other U.S. military officials had made a series of remarks suggesting Seoul’s participation in the global missile defense program would facilitate discussion on delaying the OPCON transfer set for December 2015.

Comments made by South Korea’s defense officials this week have raised speculation that Seoul and Washington have reached a deal on how to handle the two matters.

In a parliamentary audit of his ministry Monday, Defense Minister Kim Kwan-jin said the military would review measures for multilayered missile defense in addition to building a low-tier missile shield. On the following day, a ministry spokesman backed up Kim’s remarks with some details. He did not specify the additional system but excluded the Standard Missile-3, which can intercept missiles at an altitude of 400-500 km, from the list of options. His mention raised speculation that Seoul was probably seeking to adopt a system called the Terminal High Altitude Area Defense designed to shoot down short- and medium-range missiles in their terminal phase.

Seoul appears to have decided to join the U.S.-led missile defense program to the extent of meeting Washington’s call for enhanced interoperability, while hopefully deflecting a strong complaint from Beijing.

It is understandable that South Korean officials remain ambiguous on the issue of missile defense, considering its impact on relations with China and negative public opinions on its linkage with the OPCON transfer. If they have decided on what they believe as a realistically inevitable option, however, they should be more clear and specific on their stance to lessen uncertainty and uneasiness over national security.

Operating missile defense at different altitudes could provide enhanced protection against North Korea’s ballistic missiles. Seoul should explain to Beijing that Pyongyang’s increasing threats have raised the need to bolster interoperability of South Korean and U.S. missile defense systems.