South Korean Foreign Minister Kang Kyung-wha discussed countermeasures against North Korea's new missile provocation in her separate telephone talks with her counterparts in the US and Japan on Friday, the ministry said.

Her talks with US Secretary of State Rex Tillerson and Japanese Foreign Minister Taro Kono came hours after the North fired a new ballistic missile that flew over Japan.

In her talks with Tillerson, Kang expressed "deep disappointment" that the North has heightened regional tensions with the missile launch, despite global warnings, and strongly condemned the latest provocation, the ministry said.

Tillerson reaffirmed the US' unwavering commitment to helping protect South Korea, along with Japan, against any threats. 

They also agreed to take "powerful" and "stern" measures in a way that leads the North to give up its provocative behavior and come out for denuclearization talks, it added.

And they vowed to maintain "strategic" communication between the allies through diverse channels and at each level, including the upcoming UN General Assembly to be held in New York next week.

Their discussion, meanwhile, was cut short at first due to a poor connection as Tillerson was on his way back to Washington from a trip to London. They resumed their conversation on the matter after he got back to the US, a ministry official said.

Kang later held a phone conversation with Kono to discuss a coordinated approach to the matter, according to the ministry.

Kono emphasized the importance of strengthening the three-way cooperation between South Korea, Japan and the US through diverse channels including the UN Security Council so as to produce "more powerful and effective" measures against the North, the ministry said.

The back-to-back phone conversations came right after the North fired a ballistic missile from the Sunan area in Pyongyang earlier in the day that traveled around 3,700 kilometers over Japan into the North Pacific Ocean. It reached a maximum altitude of 770 km, military authorities here said.

The provocation came days after the UNSC unanimously adopted fresh sanctions, including a restriction on fuel supplies, against the North for its sixth and most powerful nuclear test denotation Sept. 3.

The North dismissed the sanctions and vowed to bolster its nuclear capabilities.

South Korea, the US and Japan have reportedly asked the Security Council to hold an emergency meeting on Friday (US time) to discuss its approach toward the North's missile launch. (Yonhap)