North Korea on Thursday said President Bush's State of the Union address was an "undisguised declaration of aggression."

In its first reaction to the speech, North Korea said it "will never allow the U.S. to wantonly encroach upon the sovereignty and dignity of the [North] and destroy its system."

"This policy speech is, in essence, an undisguised declaration of aggression to topple the DPRK system," an unidentified spokesman of the North's Foreign Ministry said in a statement carried by the North's official news agency, KCMNA. DPRK is the Democratic Peoples Republic of Korea.

Bush, in his address, said: "On the Korean peninsula, an oppressive regime rules a people living in fear and starvation."

Responding to the North's decision to withdraw from the Nuclear Nonproliferation Treaty, an international pact to prevent the spread of nuclear weapons, Bush said Pyongyang was resorting to blackmail.

"The North Korean regime is using its nuclear program to incite fear and seek concessions. America and the world will not be blackmailed," Bush said.

Striking back, the North said Bush was a "shameless charlatan."

"Bush has so far earned an ill fame as an emotional backbiter, but his recent address clearly proves that he is a shameless charlatan reversing black and white under the eyes of the world and the incarnation of the misanthropy as he rejects the people out of his favor for no reason," the North Korean spokesman said.

The North Korean official accused Bush of "trying to mislead the public opinion by spreading the rumor that the [North] is chiefly to blame for the nuclear issue."

"This is the height of shamelessness," he was quoted as saying. "We will do our utmost to defend our system in view of the U.S. declaration of aggression."

In his speech, Bush said the United States is working with South Korea, Japan, China and Russia "to find a peaceful solution" to the nuclear standoff, "and to show the North Korea government that nuclear weapons will bring only isolation, economic stagnation and continued hardship."

North Korea is demanding a nonaggression treaty with the United States before it gives up its nuclear programs. Washington has ruled out a formal treaty, but said it can provide a written security guarantee. Washington wants to bring the North's nuclear issue before the U.N. Security Council, which could eventually impose sanctions on Pyongyang.

The nuclear dispute was sparked in October when U.S. officials said North Korea had admitted having a nuclear program in violation of a 1994 agreement. Washington and its allies suspended oil shipments to North Korea -- which in turn expelled U.N. nuclear inspectors and pulled out of a global nuclear arms control treaty.