North Korea test-fired a submarine-launched ballistic missile in May, but opinion is divided on whether the image was manipulated. Photo by KCNA/Yonhap

WASHINGTON, May 20 (UPI) -- North Korea is raising its nuclear stakes -- announcing Wednesday it now has the ability to miniaturize nuclear weapons.

That statement follows an earlier claim it has successfully test-fired a submarine-launched ballistic missile, which is being refuted by a U.S. defense official.


"We have had the capability of miniaturizing nuclear warheads, as well as producing multiform weapons, for some time," North Korea's state-controlled KCNA said in a statement, according to CNN.

The miniaturization of nuclear weapons is a crucial step toward building nuclear missiles.

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The nuclear weapon is customized to fit on the top end of a ballistic missile, a challenging task that North Korea has been determined to achieve since 2013.

KCNA claimed Pyongyang can guarantee the accuracy of short-to-mid-range and also long-range rocket launches.

North Korea's latest move is placing U.S. defense calculations at a critical juncture.

According to Victor Cha, the Korea chair at the Center for Strategic and International Studies, North Korean advances in mobile intercontinental-ballistic missile capabilities could "end up undermining the state of stable deterrence that currently exists on the Korean peninsula."

Earlier in May North Korea said it had successfully conducted an underwater test of a submarine-launched ballistic missile, or SLBM.

But on Tuesday at the Center for Strategic and International Studies in Washington, U.S. Admiral James Winnefeld said the video footage of the underwater test had been manipulated.

"We saw Pyongyang raving about a test of [SLBM] capability," Winnefeld said.

"Fortunately, they've not gotten as far as their clever video editors and spin-meisters would have us believe. They are years away from developing this capability."

South Korea's Defense Ministry, however, refuted the U.S. admiral's claim on Wednesday, reported Yonhap.

An unidentified South Korean official at the ministry said both Seoul and Washington have reason to believe North Korea did successfully launch an SLBM, and that the isolated country is not far from building missile-equipped submarines.