The defense chiefs of South Korea, the United States and Japan agreed to closely cooperate in countering North Korea's evolving missile threats in their phone talks Thursday, Seoul's defense ministry said.

The talks among Defense Minister Suh Wook and his US and Japanese counterparts -- Lloyd Austin and Nobuo Kishi -- followed a series of the North's missile tests, including the launch of an intermediate-range ballistic missile (IRBM) on Jan. 30.

"The three ministers agreed that the three countries will closely cooperate in the face of North Korean missile threats and continue efforts to achieve the goal of the denuclearization of the Korean Peninsula," the ministry said in a press release.

The defense chiefs also agreed to meet in person at a "mutually agreed-upon" date, the ministry said.

At the meeting, Suh called the recent series of North Korean missile tests a "direct and serious threat" to South Korea and a "challenge to UN Security Council (UNSC) resolutions."

The North is barred from conducting any launches using ballistic missile technology under UNSC resolutions.

Suh also said that Seoul plans to strengthen both independent defense capabilities and those anchored in the "solid" US-South Korea alliance to counter Pyongyang's nuclear and missile threats.

At the talks, the US reaffirmed its "ironclad" commitment to the defense of South Korea, according to the ministry. (Yonhap)