Senior South Korean and U.S. defence officials met in Seoul on Monday to work on new guidelines to coordinate their response to any nuclear threat from North Korea, officials said. The guidelines laid out the principles and procedures for maintaining and enhancing a “credible and effective” nuclear deterrence policy and posture, according to a joint statement from the allies’ third closed-doors talks on the issue.

The Nuclear Consultative Group meeting came amid signs North Korea is racing to develop its nuclear arms and delivery systems.

Some South Korean politicians, including senior members of President Yoon Suk Yeol’s party, have called for Seoul to develop its own nuclear weapons rather than just rely on the U.S. nuclear umbrella, a step Washington opposes.

Monday’s meeting followed up on last year’s summit, when the United States promised to give South Korea more insight into its nuclear planning for any conflict with the North.

Vipin Narang, acting U.S. assistant secretary of defence for space policy who co-chaired the talks, said the guidelines set up an architecture for how the allies integrate conventional and nuclear capabilities which will be ultimately provided to each country’s leadership in a crisis. “The guidelines cover the principles and procedures for consultations, particularly in a DPRK nuclear crisis and inform alliance operational concepts and exercises,” Narang told a news conference, using the acronym of North Korea’s official name, the Democratic People’s Republic of Korea. Cho Chang-rae, South Korea’s deputy defence minister for policy, said high-level officials from both countries will hold a simulated tabletop exercise before regular summertime drills, with a focus on the possibility of North Korea using a nuclear weapon.

The two Koreas are still technically at war after their 1950-53 conflict ended in an armistice, not a peace treaty.

In late May, North Korea’s attempt to launch a military reconnaissance satellite failed after a newly developed rocket engine exploded in flight.

Seoul and Washington condemned the launch as a violation of U.N. Security Council sanctions banning Pyongyang’s use of ballistic technology.

After their second meeting in December, both sides warned that any nuclear attack by North Korea against the United States or its allies will be met with a “swift, overwhelming and decisive response” and result in the end of Kim Jong Un’s regime.

Their next meeting will be held in Washington near the end of the year, the joint statement said.