North Korea announced on Saturday that it successfully launched an underwater ballistic missile from a submarine, further raising concerns about its military capabilities and raising tensions in the region.

North Korean state media agency KCNA said that the test "proved and confirmed that the ballistic missile fire from the submarine fully met the requirements of the latest military science and technology."

KCNA added that North Korean leader Kim Jong-un said his country is now capable of "striking and wiping out in any waters the hostile forces infringing upon the sovereignty and dignity of (North Korea)."

A US State Department official said North Korea's use of ballistic missiles violates United Nations Security Council resolutions and sanctions against the country, according to CNN.

"We call on North Korea to refrain from actions that further raise tensions in the region and focus instead on taking concrete steps toward fulfilling its international commitments and obligations," the US official said.

The validity of the test has not been independently confirmed, and some officials are skeptical of the images published by North Korea. The pictures show Kim looking out with binoculars at the firing of the missile from the submarine. State media said Kim personally helped construct the weapon and oversaw the test.

If proven authentic, the test marks significant progress in North Korea's attempts to build a submarine-launched ballistic missile that could severely threaten South Korea and the surrounding area.

South Korean and US intelligence sources believe that North Korea has already installed the missile launcher onto a submarine, South Korean news agency Korea Times reported.

Also on Saturday, South Korea's government said North Korea had shot three ship-to-ship missiles from the sea. The launches came after repeated hostile threats from North Korea to shoot without warning any South Korean ships that come into disputed territory off the west coast of the Korean peninsula.

South Korea's defense ministry said if North Korea did not stop making provocative threats, "we will firmly and strongly respond so that you will regret it bitterly."