The centerpiece of the summit on Friday between President Park Geun-hye and U.S. President Barack Obama was the agreement to reconsider the current timeline for the transition of wartime operational control.

Under the current schedule, Washington is to transfer wartime OPCON to Seoul by December 2015. The transition was originally set to be completed in April 2012, but was delayed at Seoul’s request.

The request was prompted by North Korea’s torpedo attack on a South Korean Navy warship in March 2010.

Calls for another delay began to surface following the North’s third nuclear test in February last year. Seoul’s Defense Ministry made an official request for a second delay in July.

Now that the leaders of the two countries have decided to review the present timeline, it is almost certain that OPCON transition will be delayed for the second time.

The two countries are expected to finalize a new timeline in October when they hold the Security Consultative Meeting, the highest-level security cooperation body between Seoul and Washington.

As the main reason for their decision, the two leaders cited “the evolving security environment in the region, including the enduring North Korean nuclear and missile threat.”

Recently the North has threatened to undertake what it called “a new form of nuclear test.” More recently, North Korean officials warned that “something unimaginable” would take place before April 30, suggesting that the fourth nuclear test was imminent.

At the joint news conference after the summit, Park said the North “can carry out the fourth nuclear test whenever it deems necessary.”

As the North continues to escalate its nuclear and missile threats, it is necessary for Seoul and Washington to strengthen their combined defensive posture against them. In this regard, the decision to delay the OPCON transfer can be justified.

Nevertheless, the decision is likely to trigger a hot debate in Seoul and Washington. Here, opposition to delaying the transition for another time is strong even among conservatives.

Critics argue that South Korea now has the power to deter the North on its own. So, they say, it should stop relying on U.S. support and instead seek to stand on its own feet.

Many Washington officials feel the same way. Noting Seoul’s readiness to lead the combined defense, they say the transition should be promoted as scheduled.

To refute these arguments, the Korean and U.S. governments will have to present a convincing case for their decision. At the same time, they need draw up plans to enhance Seoul’s readiness to lead the combined defense and ensure there are no more delays.