The Democratic People's Republic of Korea (DPRK) said it tested an intercontinental ballistic missile on Saturday, a day after warning of an "unprecedentedly persistent, strong" response to the upcoming military exercises by the U.S. and South Korea, state media the KCNA reported.

"The surprise ICBM launching drill ... is an actual proof of the DPRK strategic nuclear force's consistent efforts to turn its capacity of fatal nuclear counterattack on the hostile forces into the irresistible one," the KCNA said.

In a separate statement on Sunday, Kim Yo Jong, vice department director of the Central Committee of the Workers' Party of Korea and younger sister of DPRK leader Kim Jong Un, bristled at the United States for trying to turn the UN Security Council into what she called a "tool for its heinous hostile policy" toward Pyongyang.

"I warn that we will watch every movement of the enemy and take corresponding and very powerful and overwhelming counteraction against its every move hostile to us," she said.

The KCNA said the missile flew 989 kilometers for 4,015 seconds, up to a maximum altitude of 5,768 km before accurately hitting a pre-set area in open waters. The Hwasong-15 was first tested in 2017.

The launch, guided by the Missile General Bureau, was conducted on an "emergency firepower combat standby order" given at dawn, followed by a written order by Kim Jong Un, the KCNA said.

(With input from Reuters)