The United States does not believe North Korea has the capacity to build nuclear warheads small enough to fit atop missiles, a White House official said Wednesday, after Pyongyang claimed it is capable of doing so.
  

The North's National Defense Commission made the claim earlier Wednesday, saying the country's "nuclear striking means have entered the stage of producing smaller nukes and diversifying them and the recent test-firing of a submarine-launched ballistic missile is part of efforts to beef up its self-defense capacity."
  

"Our assessment of North Korea's nuclear capabilities has not changed. We do not think that they have that capacity," Patrick Ventrell, a spokesman for the White House's National Security Council, said in an email to Yonhap News Agency.
  

"However, they are working on developing a number of long range missiles, including intercontinental ballistic missiles, that could eventually threaten our allies and the homeland. That is why the administration is working to improve regional and homeland missile defenses and continuing to work with the other members of the six party talks to bring North Korea back into compliance with its nonproliferation commitments," he said.
  

State Department spokeswoman Marie Harf also said the U.S. does not believe the North has mastered the miniaturization technology, but the communist regime has been working on developing missiles "that could eventually threaten our allies, our partners."
  

"That's obviously something we're very concerned about in terms of that capability," she said at a regular briefing, referring to the North's missile capabilities. "We just don't think they have it (the miniaturization capacity)."
  

This assessment, however, runs counter to the military's assessment.
  

Last month, Adm. William Gortney, commander of the U.S. Northern Command, said the North is believed to be capable of miniaturizing nuclear warheads to be put on its new KN-08 intercontinental ballistic missile and fire it at the U.S. mainland.
  

In March, Adm. Cecil Haney, commander of the U.S. Strategic Command, also told a Senate Armed Services Committee hearing that he believes the North has "already miniaturized" some of its nuclear weapons.
  

And in October, Gen. Curtis Scaparrotti, commander of U.S. Forces Korea, said that as USFK commander, he assumes the North has the capabilities to miniaturize nuclear warheads and that the country has "the technology to potentially actually deliver what they say they have."
  

North Korea has conducted three underground nuclear tests so far, in 2006, 2009 and 2013. The country has also conducted a series of long-range missile or rocket launches since 1998. In its most recent launch in late 2012, the North succeeded in putting a satellite into orbit.
  

Analysts have warned that it is only a matter of time until the North develops nuclear-tipped missiles. Some experts have recently warned that the communist nation's nuclear arsenal could expand to as many as 100 bombs by 2020.
  

The six-party talks aimed at resolving the North Korean standoff have been stalled since late 2008. North Korea demands the unconditional resumption of negotiations, while the U.S. says that Pyongyang must first take concrete steps demonstrating its denuclearization commitments. (Yonhap)