North Korea claimed on Wednesday it has been able to miniaturize nuclear warheads, making them small enough to fit on a missile, the Washington Post reported.

If verified, the development would "mark a major advance in the country's military capabilities and the threat it can pose to the world."

The country "has reached the stage of ensuring the highest precision and intelligence and best accuracy of not only medium- and short-range rockets, but long-range ones," its official Korean Central News Agency said based on announcements by the National Defense Commission, chaired by dictator Kim Jong Un.

Although the North's totalitarian regime has a tendency to exaggerate its technical abilities, as the Washington Post cautioned, the admiral who heads the agency charged with protecting U.S. airspace had warned as early as last month that Pyongyang had the capability to hit the West Coast of the United States with a nuclear weapon mounted onto an intercontinental ballistic missile.

"Our assessment is they have the ability to put a nuclear weapon on a KN-08 (mobile launcher) and shoot it at the homeland, and that's the way we think -- that's our assessment of the process," Adm. William Gortney, the North American Aerospace Defense Command chief, said in early April, according to Defense News.

On Wednesday, however, U.S. officials responded with skepticism to the announcement made by Kim's regime, CNN noted.

"Our assessment of North Korea's nuclear capabilities has not changed," National Security Council spokesman Patrick Ventrell said in a statement. "We do not think that they have that capacity," he added.

Ventrell insisted, however, that his remarks should not be misinterpreted as a lack of concern regarding the North Koreans' nuclear program.

"They are working on developing a number of long range missiles, including intercontinental ballistic missiles, that could eventually threaten our allies and the homeland," he admitted.

"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," Ventrell added.