The Korean Central News Agency, quoting the North Korean Foreign Ministry, said Wednesday it was natural for the country to bolster its missile capability to strike what it called the stronghold of U.S. aggression.
China's Xinhua News Agency, which carried the latest report, said the Foreign Ministry said the North had "strategic rocket forces that could bring the U.S. mainland and other military bases within range."
In a similar claim earlier, the North said the U.S. mainland was now within striking range of its strategic forces, which has already been termed "bragging" by the United States.
The North Korean statements follow an announcement by South Korea that the United States had agreed to allow Seoul to expand the strike range of its missiles under their 1979 agreement, saying the main objective of the new guidelines was to counter armed provocations from North Korea.
The North is already under U.N. resolutions to suspend its ballistic missile program activities.
In the latest statement, Xinhua said an unnamed North Korean spokesman also denounced the United States as the primary cause of a new missile arms race in northeast Asia.
"The U.S. threw cold water over the effort for stability of the Korean Peninsula and its surrounding areas, and destroyed the foundation for dialogue and negotiations," the spokesman said.
U.S. State Department spokeswoman Victoria Nuland had dismissed the North's earlier claim, saying "rather than bragging about its missile capability, they [the North] ought to be feeding their own people."
She said the North needs to understand it will achieve "nothing by threats or provocations."
She also said the U.S. and South Korean missile guidance agreement are defensive in nature.
The New York Times has reported that while it is difficult to estimate the secretive North's missile capabilities, military experts and South Korean government officials have said that country has already deployed ballistic missiles capable of reaching targets as far away as Guam.