It is noted that this is the sixth missile launch since the end of July. "Juche" refers to the North's national ideology of self-reliance.
Pyongyang's Korean Central News Agency, or KCNA, said that following Friday's launches, Kim expressed "great satisfaction" over his military's "mysterious and fantastic success rates" in recent testing activity and vowed to build up "invincible military capabilities no one dare provoke". "The national defense scientists showed a ideal result in the test-fire, too, and helped cement bigger confidence in this weapon system".
"It is our party's goal of defence building to possess invincible military capabilities no one dares provoke and to keep bolstering them", Kim was quoted as saying.
The North's statement came hours before South Korea's military detected two projectiles North Korea fired into the sea to expand a torrid streak of weapons display that's apparently aimed at pressuring Washington and Seoul over their joint drills and slow nuclear negotiations.
"We think the range could probably hit all of South Korea and parts of Japan".
Pyongyang has denounced such exercises as a rehearsal for an invasion. Washington and Seoul insisted that drills, the latest of which began on Monday, were purely defensive in nature.
They were "presumed to be short-range ballistic missiles", a US Joint Chiefs of Staff official said, adding that further analysis would be required to confirm that.
Military experts say that the projectiles bear outward similarities to the US' Army Tactical Missile System, a surface-to-surface missile system.
U.S. Special Representative for North Korea Stephen Biegun, center, is questioned by reporters upon his arrival at Incheon International Airport in Incheon, South Korea, Feb. 3, 2019.
Esper said the USA won't overreact to the missile tests.
US allies are "quite concerned about it", Bolton said in an interview with the Voice of America.
Mr Trump has also made it public in tweets that he too wants to pressure Seoul to pay more to host United States troops, and described the current joint military drills as expensive.
Experts, however, say the launches show advances in North Korea's development of a new guided rocket artillery system and short-range ballistic missile systems that can be launched from mobile platforms.
North Korea said on Friday it will never sit down with South Korea for talks again, rejecting a vow by the South's President Moon Jae-in to pursue dialogue with Pyongyang made the previous day as he pledged to bring in unification by 2045.
"We have no more words to talk with South Korean officials", the official said in a statement carried by the state-run Korean Central News Agency. Trump and Kim have met twice since their first summit in Singapore past year and said their countries will continue talks, but little progress has been made on the North's stated commitment to denuclearise.
Kim said it was "an occasion to send an adequate warning to the joint military drill now underway by the US and South Korean authorities", according to KCNA.