North Korea will boost its nuclear deterrent force to protect itself against war, a foreign ministry spokesman said in an official Korean Central News Agency (KCNA) report.
The US plan "is the most outright hostile act against the DPRK (North Korea) as it is a system to wage a war against the DPRK and, furthermore, a part of its unchallenged attempt to dominate the Asia-Pacific region," the spokesman said.
"The DPRK will increase its nuclear deterrent force in every way and take a decisive counter-measure for self-defence when necessary in order to avert a war and defend peace in the Korean peninsula and the rest of northeast Asia," he said.
The planned deployment and US and Japan military exercises "indicate that they are stepping up the preparations for the second Korean war in real earnest behind the scene of dialogue and this has already gone beyond the danger line," he said.
The US plan to deploy the destroyer equipped with the Aegis radar-combat system in the Sea of Japan (East Sea) in September has been welcomed by Japan as a deterrent against ballistic missiles.
Japan has been conducting joint research with the United States on developing a sophisticated missile defence system since 1999, a year after North Korea launched a ballistic missile over the Japanese islands and into the Pacific.
The United States has demanded that North Korea completely and verifiably dismantle its nuclear programmes. Two rounds of six-nation talks on the impasse have made little progress.