PYONGYANG, North Korea — North Korea said Saturday that it successfully test-fired a newly developed ballistic missile from a submarine in what would be the latest display of the country’s advancing military capabilities.
Hours after the announcement, South Korean officials said the North fired three antiship cruise missiles into the sea off its east coast.
Experts in Seoul say North Korea’s military demonstrations and hostile rhetoric are attempts at wresting concessions from the United States and South Korea, whose officials have recently talked about possibly holding preliminary talks with Pyongyang to test its commitment to denuclearization.
For the second straight day, North Korea said it would fire without warning at South Korean naval vessels that it claims have been violating its territorial waters off the west coast of the Korean Peninsula.
South Korea’s presidential Blue House held an emergency national security council meeting to review the threat and discuss possible countermeasures.
‘‘By raising tensions, North Korea is trying to ensure that it will be able to drive whatever future talks with the US and South Korea,’’ said Yang Moo-jin, a professor at the Seoul-based University of North Korean Studies.
South Korean officials previously had said North Korea was developing technologies for launching ballistic missiles from underwater, although past tests were believed to have been conducted on platforms built on land or at sea and not from submarines.
Security experts say that North Korea acquiring the ability to launch missiles from submarines would be an alarming development because the missiles are harder to detect before launch than land-based ones. North Korea already has a considerable arsenal of land-based ballistic missiles, and is also believed to be advancing in efforts to miniaturize nuclear warheads to mount on them, South Korean officials say.
North Korean leader Kim Jong Un personally directed the submarine test launching and called the missile a ‘‘world-level strategic weapon’’ and an ‘‘eye-opening success,’’ according to the country’s official news service. The report by the Korean Central News Agency, or KCNA, did not provide the timing or location of the launch.
Kim also declared his country now has a weapon capable of ‘‘striking and wiping out in any waters the hostile forces infringing upon the sovereignty and dignity” of North Korea.
North Korea’s state-run Rodong Sinmun newspaper published photos of a projectile rising from the sea and Kim smiling from a distance at what looked like a submarine.
The test might have taken place near the eastern coastal city of Sinpo, where satellite imagery in recent months, analyzed by a US research institute, appeared to show North Korea building missile-testing facilities and equipping a submarine with launch capabilities.
In Washington, the State Department said it was aware of the reports about the firing of the submarine missile, and noted that launches using ballistic missile technology are ‘‘a clear violation’’ of multiple UN Security Council resolutions.
The United States urged 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.’’
South Korea’s defense ministry had no immediate comment on the claim of a successful test.
Ministry officials have previously said North Korea has about 70 submarines, and appears to be mainly imitating Russian designs in its efforts to develop a system for submarine-launched missiles.
Uk Yang, a Seoul-based security expert and an adviser to the South Korean military, said it is unlikely that North Korea possesses a submarine large enough to carry and fire multiple missiles. However, it’s hard to deny that Pyongyang is making progress on dangerous weapons technology, he said.
The website 38 North, operated by the US-Korea Institute at the Johns Hopkins School of Advanced International Studies, said in January that such capability posed a potential new threat to South Korea, Japan and US bases in East Asia, although experts say North Korea’s submarines tend to be old and would be vulnerable to attack.
Meanwhile, a South Korean Joint Chief of Staff official said the North fired three anti-ship cruise missiles into the sea within a span of an hour early Saturday evening from an area near the eastern port city of Wonsan. The official, who spoke on condition of anonymity, citing office rules, identified the missiles as KN-01 missiles, which the North also test-fired in February in an event personally attended by North Korean leader Kim.
There had been expectations that Kim would attend the Victory Day celebration in Russia on Saturday for his international debut, but North Korea sent to Moscow the head of its rubber-stamp parliament instead.Associated Press writer Tong-hyung Kim in Seoul, South Korea, contributed to this report.