North Korea has reacted furiously to plans by Japan to purchase cruise missiles from the United States.

Japan's Defense Ministry last month signed a contract to buy up to 400 US Tomahawk missiles. The purchase is part of Japanese efforts to acquire counterstrike capabilities against enemy missile bases and other targets.

Pyongyang described the move as showing how Japan has become "hell-bent" on obtaining long-range missiles targeting neighboring countries.

In a statement, the North's foreign ministry said Japan has become the "worst threat-posing country in the region." The comment was published on Saturday by the Korean Central News Agency under the name of a researcher at the Institute for Japan Studies.

The statement also attacked the US for providing the Tomahawks, describing the move as part of a "hegemonic strategy" by Washington against North Korea, China and Russia.

Pyongyang has been ramping up its harsh rhetoric. The ruling Workers' Party newspaper, Rodong Sinmun, in a report on a crash of a US fighter jet over the Yellow Sea, recently described South Korea as a "puppet nation."

Radio Press, which monitors North Korean media, says this is the first time the North has referred to the South in such a way.

Pyongyang appears to be underscoring its new policy framing the South as a hostile enemy nation instead of a party to be reunited with.