North Korea claimed Wednesday that it has the ability to miniaturize nuclear weapons that can fit atop its missiles, media reports said, citing the North's official Korean Central News Agency (KCNA). The news comes just a day after a top U.S. military officer expressed skepticism about the country's ability to deploy ballistic missiles.

"It is long since the DPRK's [Democratic People's Republic of Korea] nuclear striking means have entered the stage of producing smaller nukes and diversifying them," a spokesman for North Korea's National Defense Commission said, according to South Korean news agency Yonhap, which cited KCNA. "The DPRK 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."

North Korea had recently claimed that it successfully test-fired a ballistic missile from a submarine in early May. However, U.S. Adm. James Winnefeld said at the Center for Strategic & International Studies in Washington on Tuesday that photos showing the launch were manipulated by state propagandists, the Associated Press reported.

“They have not gotten as far as their clever video editors and spinmeisters would have us believe,” Winnefeld, who is the vice chairman of the Joint Chiefs of Staff, reportedly said. “They are many years away from developing this capability. But if they are eventually able to do so it will present a hard-to-detect danger for Japan and South Korea as well as our service members stationed in the region.”