North Korea said the test was carried out on Wednesday using the first-stage, solid-fuel engine of an intermediate-range ballistic missile.
The dispatch came a day after South Korea's military said North Korea had launched what appeared to be a hypersonic missile off its east coast that exploded in midair.
KCNA said the missile succeeded in separating warheads, which were accurately guided to three preset targets, in a test that was aimed at developing multiple independently targetable re-entry vehicle technology.
"The purpose was to secure the capability to destroy individual targets using multiple warheads," it said.
South Korea's military said a joint analysis by the South and the US military points to the missile's blowing up in its initial stage of flight.
"Today North Korea disclosed something, but we believe it's simply a means of deception and exaggeration," Lee Sung-joon, the spokesman for South Korea's Joint Chiefs of Staff, told a briefing on Thursday.
The photos released by the North purporting to be of Wednesday's test were also most likely fabricated or recycled pictures from a previous launch, he said.
South Korea, the United States and Japan condemned the launch as a violation of UN Security Council resolutions and a serious threat, and warned against additional provocations after last week's summit between North Korean leader Kim Jong-un and Russian President Vladimir Putin.
On Thursday, the three countries began large-scale joint military drills involving navy destroyers, fighter jets and the nuclear-powered US aircraft carrier Theodore Roosevelt, aimed at boosting defence against missiles, submarines and air attacks.
During Putin's first visit to North Korea in 24 years, the two leaders signed a mutual defence pact, which Kim lauded as an alliance, but which South Korean President Yoon Suk-yeol called "anachronistic".
On Thursday, South Korea announced sanctions on four entities, two Russian shipping companies among them, as well as four Russian vessels, for involvement in illegal shipments of weapons and petroleum products.
South Korea and the United States have accused the North of supplying weapons to Russia that are being used in the Ukraine war.Â
Both Russia and North Korea deny any such transactions.
South Korea separately sanctioned a North Korean entity and eight individuals for missile development projects.
In a separate KCNA report, North Korean defence minister Kang Sun Nam condemned Ukraine's attack on Crimea with US-supplied ATACMS missiles that Russia said killed at least four people and injured 151 as an "inexcusable, heinous act against humanity".
The attack highlighted how Washington has served as a "top-class state sponsor of terrorism", he said.
The US State Department said on Monday Washington provided weapons to Ukraine so it could defend its sovereign territory, including Crimea.
