North Korea on Wednesday ruled out further negotiations with the United States, and threatened to react with nuclear strikes and cyber warfare to any U.S. attempt to ignite “a war of aggression.”

In an apparent reaction to recent comments from U.S. President Barack Obama, who spoke of an eventual collapse of the North Korean regime, the country’s National Defence Commission (NDC) said that Obama’s statement revealed Washington’s goal to “bring down” North Korea. NDC, the country’s top military body, is headed by North Korean leader Kim Jong Un.

“Since the gangster-like U.S. imperialists are blaring that they will ‘bring down’ the DPRK [Democratic People's Republic of Korea]... the army and people of the DPRK cannot but officially notify the Obama administration of the USA that the DPRK has neither need nor willingness to sit at the negotiating table with the U.S. any longer,” NDC said in a statement, obtained by Reuters.

In an interview with YouTube last month, Obama had called North Korea “the most isolated, the most sanctioned, the most cut-off nation on Earth.” He also said that “a regime like this” would eventually fall. Obama’s statement was followed by an angry reaction from Kim, who said that Pyongyang will not sit idly “with rabid dogs barking” about toppling its socialist system.

“If the U.S. ignites a war of aggression against the DPRK by conventional forces, it will fight it by conventional forces of its style, if the former unleashes a nuclear war against the latter, it will counter it through its own nuclear strikes,” NDC said in a statement, carried by the Korean Central News Agency (KCNA), the North’s state-run news agency.

“And if the former tries to bring down the latter through a cyber warfare, it will react to it with its own preeminent cyber warfare and will thus bring earlier the final ruin of the U.S.,” NDC said, adding that Pyongyang had decided “to write the last page of ... U.S. history.”

The NDC statement came after North Korea said Sunday that the U.S. had rejected an invitation extended by the North to a senior American official. Pyongyang had invited Sung Kim, the U.S. special representative for North Korean policy, but the talks did not take place as the U.S. refused to take part in any dialogue unless the North proved it was serious about denuclearization, Agence France-Presse reported.