South Korean and US top envoys on North Korea agreed Thursday to seek more retaliatory action against North Korea's recent launch of a submarine-launched ballistic missile (SLBM), Seoul's Foreign Ministry said.

    The ministry's special representative for Korean Peninsula Peace and Security Affairs Kim Hong-kyun held a telephone conversation with Sung Kim, US special representative on North Korean policy earlier in the day, the ministry said in a brief note to the media.

    The call was arranged one day after North Korea fired off an SLBM in the East Sea, the third sub launched missile the country has launched so far this year. The projectile flew about 500 kilometers before landing in waters near Japan, drawing condemnation from Seoul, Tokyo and Washington as well as the United Nations Secretary-General Ban Ki-moon.

    "Both sides shared the seriousness and graveness of North Korea's recent provocations and agreed to cooperate closely in order to induce a reaction at the international organization level including the United Nations Security Council," the ministry said. The envoys also vowed to maintain a solid combined defense posture against North Korea, Yonhap news agency reported. "In addition, they agreed to examine additional measures in response to the provocations," according to the ministry. 

    The allies will cement their collaboration further to keep sending messages of pressure on North Korea at both multilateral and bilateral levels, including at the approaching session of the East Asia Summit, it said.

Source: QNA