SEOUL -- South Korea and the United States agreed on Saturday to mount pressure on the Democratic People's Republic of Korea (DPRK), as the DPRK was holding its party congress for the first time in 36 years.

South Korean Foreign Minister Yun Byung-se phoned with US Secretary of State John Kerry earlier in the day and reached the agreement, the ministry said in a press release.

"(They) agreed to keep sending strong warning messages together with the international community to deter additional nuclear tests and provocations by the DPRK," the ministry said.

The DPRK leader Kim Jong Un on Friday celebrated the "great success" of the country's nuclear program at the seventh congress of the ruling Workers' Party.

The two officials also shared their assessment of the DPRK's ongoing ruling party congress and the possibility of further "provocations" by Pyongyang, according to the press release.