( CNN ) -- 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 wo n'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 can not 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 . '' 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 . U.S. to beef up missile defense against North Korea , Iran . 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 . ''
North Korea has been targeted internationally for its budding nuclear weapons program . The U.S. and South Korean militaries have conducted more than 60 missile tests since 2006, including a recent test of an intercontinental ballistic missile. North Korea 's nuclear arms `` can not be disputed ( if there 's a ) U.S. nuclear threat '' Pyongyang denies its using nukes as a `` bargaining chip '' to win economic concessions .