Kim said the North could try other forms of provocation, including border clashes and cyber attacks.

Pyongyang's latest missile deployment has prompted the US to move its THAAD advanced missile defense system along with radar systems to a base on the Pacific Ocean island of Guam.

On Wednesday, the North Korean army said it had received approval to launch a “merciless” attack on the United States, including possible nuclear strikes.

The statement follows a pledge by Pyongyang on Tuesday to restart facilities at its Yongbyon nuclear complex, including a uranium enrichment plant and a reactor.

EU foreign policy chief Catherine Ashton on Thursday deplored North Korea‘s decision to restart its Yongbyon facilities.

"The continued breaking of its international obligations by the DPRK that threaten stability in the region will inevitably lead to an ever more united response by the international community," Ashton warned.

"The DPRK should refrain from fuelling further tensions and show commitment to the agreed goal of complete, verifiable and irreversible denuclearization of the Korean Peninsula."

In another sign of tension between the two nations, North Korea announced on Wednesday it would prevent South Korean workers and managers from entering the Kaesong Industrial Complex, located on the North's side of the border but housing scores of South Korean companies.

North Korea has demanded the withdrawal of South Korean workers from the complex by April 10, Yonhap said Thursday. More than 50,000 North Koreans work in the zone, producing hundreds of millions of dollars worth of goods each year.

Seoul said it "deeply regrets" the North's decision to stop South Koreans from entering Kaesong while Defense Minister Kim Kwan-jin said military action could be taken if the safety of the South Koreans in the zone came under threat.

UN Secretary General Ban Ki-moon on Thursday urged North Korea to lift the restrictions on South Korean workers there.

Tensions began to rise on the Korean Peninsula after international sanctions were imposed on North Korea in response to a long-range rocket launch in December that the permanent members of the UN Security Council condemned as a ballistic missile test.