Story highlights North Korea has been targeted internationally for its budding nuclear weapons program

Its government, as reported by state news, blasts the "hostile policy" of the U.S., others

North Korea's nuclear arms "cannot be disputed (if there's a) U.S. nuclear threat"

Pyongyang denies its using nukes as a "bargaining chip" to win economic concessions

A day after the United States promised new missile defense interceptors to guard against a North Korean attack, Pyongyang responded Saturday by blasting the Americans' "hostile policy" and saying it won't negotiate with them over its nuclear program.

"(North Korea's) nuclear weapons serve as an all-powerful treasured sword for protecting the sovereignty and security of the country," a foreign ministry spokesman said, according to the state-run KCNA news agency. "Therefore, they cannot be disputed ... as long as the U.S. nuclear threat and hostile policy persist."

The stern statement marked the latest in the war of words, and more, pitting North Korea against the United States and, in fact, many other countries worldwide.

Tensions have escalated since December, when North Korea successfully launched a long-range rocket for the first time under what the United States and other Western nations say was the guise of putting a satellite into orbit.

They rose to yet another level when North Korea launched a nuclear test last month, prompting the U.N. Security Council to agree on stepped-up sanctions intent on pressuring Pyongyang.

In Saturday's statement, the North Korean foreign ministry spokesman claimed the United States "hostile policy ... has become more pronounced."

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Washington's latest salvo on this front came Friday, when U.S. Defense Secretary Chuck Hagel said 14 more missile interceptors -- bringing the total to 44 -- will be in place on the West Coast by 2017 to guard against a possible North Korean attack.

North Korea blamed the United States on Saturday for "having compelled (North Korea) to have access to nukes" because it "escalated the situation of the Korean Peninsula to an extreme phase."

The statement challenged claims that North Korea was pursuing its nuclear program as a "bargaining chip" to gain economic benefits through negotiations, such as food and other humanitarian aid.

"The U.S. poor temptation that it would help (North Korea) if the latter makes other choice(s) may work on other countries, but it sounds nonsensical to (North Korea)," the foreign ministry spokesman said. "(North Korea) has no idea of negotiating with the U.S. unless it rolls back its hostile policy."