"Unimaginable, astonishing incidents and events" are occurring because of the "gangster-like" greed of hegemonic forces, making confrontations around the world more violent, Kim said, blaming the US for worsening bloodshed in Europe and the Middle East.
Kim spoke at a Central Committee meeting of the ruling Workers' Party, which began on Saturday and closed on Monday, KCNA said.
Kim accused the US and South Korea of making the security situation on the Korean Peninsula more dangerous by steadily upgrading their combined nuclear posture, the only purpose of which, he said, is to attack North Korea.
"To steadily expand and strengthen the nuclear forces ... and to thoroughly exercise the position of a nuclear weapons state is the most correct and unique way to actively and confidently cope with the unpredictable international military and political situation getting complicated in multiple ways," KCNA said.
KCNA did not elaborate on specific actions regarding the country's nuclear arsenal that might be taken.
Kim also ordered the buildup of conventional weapons and an acceleration of the construction of a 10,000-tonne strategic guided missile cruiser, KCNA said.
North Korea has defied a slew of sanctions imposed by both the United Nations and the US between 2006 and 2017 banning Pyongyang from developing nuclear weapons and ballistic missiles to deliver them. Its stance has alarmed regional powers.
It has declared itself a nuclear state and has said nothing would convince it to abandon its atomic weapons, despite years of diplomatic efforts by the US, China and South Korea.
