North Korea on Thursday claimed it has succeeded in test-firing an intermediate-range ballistic missile, vowing to strengthen its capacity to wage nuclear strikes against the United States.

The Korean Central News Agency said that the North successfully carried out the test-fire of the medium long-range strategic ballistic missile named Hwasong-10.

"The test-fire was successfully conducted without giving any slightest effect to the security of surrounding countries," the KCNA said, adding that North Korean leader Kim Jong-un watched the test.

On Wednesday, North Korea fired off what is believed to be two Musudan mid-range missiles from the east coast city of Wonsan, the South Korean military said.

The first launch is presumed to have ended in failure. But the second missile, fired at a higher angle, flew some 400 kilometers and reached an altitude of about 1,000 km, which analysts say is an indication that the North may have fixed problems that have plagued the Musudan missile in the past.

Wednesday's back-to-back tests marked the communist country's fifth and sixth flight-tests of the Musudan missiles since April.

North Korea's previous four tests all ended in failure. "It is needed to increase in a sustained way our pre-emptive nuclear attack capability and continue the study and development of diverse strategic attack weapons," Kim was quoted as saying by the KCNA. "The current test-fire marked an important occasion in further strengthening the nuclear attack capacity of our state." The Musudan missile, with an estimated range of some 3,000 to
4,000 kilometers, could theoretically fly as far as the U.S. territory of Guam.

The North's latest move raises concerns about advances made in the North's nuclear and missile program as Pyongyang is seeking to develop a nuclear-tipped intercontinental ballistic missile capable of hitting targets in the U.S. mainland.

North Korea claims that it has made progress in its nuclear and missile capabilities, including the miniaturization of nuke bombs and atmospheric re-entry technology. Outside experts raised doubts about the North's claims.

A set of United Nation Security Council resolutions ban North Korea from using ballistic missile technology. Pyongyang said that its nuclear weapons program is a powerful deterrent against what it called Washington's hostile policy toward it.

The UNSC slapped its toughest sanctions to date on North Korea for its fourth nuclear test in January and long-range rocket test in the following month.

South Korea condemned North Korea for making another provocation, calling the latest launch a clear violation of existing U.N. resolutions.

The UNSC is expected to hold an emergency meeting Wednesday (New York time) to discuss North Korea's latest firings of the Musudan missiles, according to a U.N. official.

Next week, the country will convene the main meeting of its rubber-stamp parliament, the Supreme People's Assembly, an event that will be used as a venue to reaffirm the unfettered power of the North's leader. (Yonhap)