PYONGYANG, North Korea — North Korea said it will never negotiate away its nuclear weapons in the face of hostility, after the U.S. disclosed plans to bolster missile defenses against a potential attack by the totalitarian regime.

“The U.S. is seriously mistaken if it thinks that the DPRK had access to nukes as a bargaining chip,” the official Korean Central News Agency said Sunday. North Korea has “no idea of negotiating with the U.S. unless it rolls back its hostile policy.”

The U.S. is taking several steps to bolster missile defenses and “stay ahead of the threat” posed by Iran and North Korea, Secretary of Defense Chuck Hagel told reporters Friday at the Pentagon. The U.S. will add 14 interceptors to the 30 in its missile-defense system by fiscal 2017, he said.

Hagel’s announcement came as Deputy Defense Secretary Ashton Carter prepared to travel to Asia, with stops including South Korea.

Tensions on the Korean peninsula are at the highest since at least 2010, with North Korea threatening nuclear strikes and withdrawing from the 1953 armistice ending the Korean War.

A North Korean military unit fired short-range missiles into the sea off the nation’s east coast, South Korea’s Yonhap News reported Friday, citing an unnamed military person in Seoul. South Korea and the U.S. Monday began their “Key Resolve” exercise.

‘Treasured Sword’

“The DPRK’s nuclear weapons serve an all-powerful treasured sword for protecting the sovereignty and security of the country,” according to a statement carried by KCNA yesterday. “They cannot be disputed even in the least as long as the U.S. nuclear threat and hostile policy persist.”

DPRK stands for North Korea’s official name, the Democratic People’s Republic of Korea.

There’s no evidence that North Korea has nuclear-armed ballistic missiles to target the U.S. or South Korea. There’s also no public information on whether North Korea has been able to covertly advance beyond testing to weaponizing a nuclear device.

“North Korea’s claims may be hyperbolic — but as to the policy of the United States, there should be no doubt: We will draw upon the full range of our capabilities to protect against, and to respond to, the threat posed to us and to our allies by North Korea,” U.S. National Security Adviser Thomas Donilon said in last Monday's  speech to the Asia Society in New York.

The intelligence community’s annual global threat assessment, presented to Congress last week by Director of National Intelligence James Clapper, cited “North Korea’s commitment to develop long-range missile technology that could pose a direct threat to the United States.”

‘Much-Needed Protection’

Sen. James Inhofe, the top Republican on the Senate Armed Services Committee, said Friday that adding interceptors will provide “a much-needed measure of protection” against North Korea.

In addition to deploying the 14 additional interceptors, Hagel reaffirmed the U.S. pledge to deploy in Japan a second TPY-2 missile defense radar.

The 14 added interceptors will be located in Alaska and will cost $1 billion, which the Pentagon will request in its fiscal 2014 budget, according to James Miller, under secretary of defense for policy.