Seoul, South Korea (CNN) North Korean leader Kim Jong Un said the country would not use a nuclear weapon unless its sovereignty is encroached by "invasive hostile forces with nuclear weapons," according to the country's state news agency KCNA.

He made the remarks Saturday at the ruling Workers' Party of Korea's Seventh Congress in Pyongyang, which began the day before.

Kim also reportedly said North Korea will faithfully fulfill its nuclear nonproliferation obligations and make an effort to realize global denuclearization.

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In his 15-minute opening speech Friday , Kim touted the country's weapons development, saying they had "elevated our respect to the world and enemies."

In January, Pyongyang announced that it had successfully tested a thermonuclear device, which, if true, would mark a significant advance in its nuclear capabilities.

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