(LEAD) FM agrees with Kerry to step up efforts to put together strong sanctions on N. Korea

(ATTN: UPDATES with State Department readout)

SEOUL, Feb. 8 (Yonhap) -- Foreign Minister Yun Byung-se and U.S. Secretary of State John Kerry agreed Sunday to step up diplomatic efforts to put together strong sanctions on North Korea for conducting a banned long-range rocket launch just a month after a nuclear test, officials said.

Yun and Kerry spoke by phone for about 20 minutes after the North defied international warnings and launched the rocket in violation of U.N. Security Council resolutions. The successful launch showed the North is moving closer to developing an intercontinental ballistic missile capable of reaching the U.S.

It was their fourth phone conversation after the North's Jan. 6 nuclear test.

Officials said that the two top diplomats shared an understanding on the need for the international community to send a firm and united message to Pyongyang through a U.N. Security Council resolution and various unilateral sanctions, just as shown in the Iranian nuclear deal.

Kerry reaffirmed Washington's iron-clad commitment to South Korea's defense, saying the U.S. will safeguard the ally's security and take all measures necessary to cope with North Korean provocations, officials said.

Official said Yun plans to use his attendance at the Munich Security Conference and his visit to the United Nations next week to drum up international support for unilateral sanctions on the North.

Yun and Kerry also agreed to hold a meeting on the sidelines of the Munich Security Conference.

In Washington, the State Department said that Kerry also spoke with his Japanese counterpart.

"The secretary reaffirmed for both foreign ministers the U.S. ironclad commitment to the security and defense of Japan, the Republic of Korea, and our other allies," the department said in a readout.

"The secretary condemned the launch as a violation of multiple U.N. Security Council Resolutions that threatened international peace and security, and he emphasized the importance of a united international response to North Korea's provocations, including through a strong U.N. Security Council Resolution," it said.

Kerry also noted the vital importance of continued close communication and cooperation among the three countries in addressing the threats posed by North Korea, it said.
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