North Korea says a recent U.S. anti-missile system upgrade in South Korea is a provocative step that could undermine future talks about Pyongyang's nuclear weapons program.

North Korea's official news agency on Friday angrily denounced the deployment of new U.S. Patriot anti-missile systems unveiled earlier this week by U.S. forces as a preparation for war on the Korean Peninsula. The dispatch called the U.S. move a barrier to resolving the crisis over Pyongyang's nuclear programs.

The North Korean statement repeated Pyongyang's view that as long as Washington maintains what it calls a "hostile" policy, then the North reserves the right to maintain and strengthen a nuclear deterrent force.

U.S. intelligence analysts say it is likely that North Korea already possesses one or two nuclear weapons. Analysts fear that as time passes, Pyongyang's nuclear capability will grow and harden its negotiating position in any future talks with the United States and other countries.

The U.S. military says the new Patriot Advanced Capability-3 system deployed in South Korea can destroy ballistic missiles, cruise missiles and aircraft. It says the Patriots - part of an $11 billion plan to enhance defenses in South Korea - were deployed in July but not publicized until this week, after troops were trained to operate the system.

The United States and four other regional powers - China, Japan, Russia and South Korea - sought in talks in Beijing last month to persuade North Korea to give up its nuclear weapons program. Those talks ended inconclusively, and there are no definite plans to meet again.

The United States has refused North Korean demands for a non-aggression pact in exchange for scrapping its nuclear arms drive, leaving the two nations deadlocked.

The crisis began 11 months ago, when Washington said North Korea had admitted having a nuclear program in violation of several international accords. Since then, Pyongyang has expelled international nuclear inspectors and restarted a facility capable of producing fuel for nuclear weapons.

Washington is also concerned about the North's ballistic missile program. North Korea has missiles that can reach Japan and beyond, and there are fears that a new missile is being developed that could hit the United States.

Pyongyang already has about 10,000 artillery pieces within range of Seoul. Military experts say the North Koreans can rain more than one hundred thousand shells an hour onto the South's capital, and the U.S. Patriot system would not be able to stop such a barrage.