The reports are the latest to suggest the country may soon follow through on threats to resume testing long-range ICBMs or nuclear weapons for the first time since 2017.
Kim said that he would "steadily develop the relations between the two parties and the two countries to a new high stage."
North Korea fired a suspected ballistic missile off its east coast, posing a threat to neighbors South Korea.
The young, reclusive leader's disappearance from state media often sparks speculation over his health or whereabouts.
North Korean leader Kim Jong Un has been pushing for education reform in recent years by spurring technological and scientific innovation.
North Korea's economy has been battered by years of sanctions over its nuclear and weapons programs, and heavy rains and floods have also taken a toll.
Addressing the UN General Assembly on Tuesday, South Korean President Moon Jae-in repeated a call for a formal end to the war but later said time is running out to achieve such progress.
Pyongyang has been steadily developing its weapons program amid a standoff over talks aimed at dismantling its nuclear and ballistic missile programs in return for US sanctions relief.
North Korea also conducted a cruise missile test just hours after US President Joe Biden took office in late January.
South Korea's defense ministry said on Monday the timing, scale and formation of the drills were not yet finalized. The US Forces Korea declined to comment, citing its policy.