U.S. nuclear envoy Jung Pak and South Korean counterpart Kim Gunn have met in Seoul to discuss high tension in the Korean peninsula.

The officials, who were scheduled to meet later with Japan’s nuclear envoy, talked to find ways to respond to North Korea’s nuclear threats.

The North’s leader Kim Jong Un has been on a provocative run of weapons testing and threats that raised regional tensions to the highest point in years.

Kim has declared that North Korea would abandon its long-standing commitment to a peaceful unification with South Korea.