North Korea reported on the drill a day after its neighbors said they detected multiple ballistic missile launches and accused the North of carrying out provocations.

North Korean leader Kim Jong Un, right, inspecting a missile launch exercise in Pyongyang on Sunday.STR / AFP - Getty Images

North Korea said Monday that leader Kim Jong Un observed test-flights of hypersonic missiles and underscored the need to bolster the country`s nuclear war deterrent, as the country dials up weapons displays ahead of its major political conference.

North Korea reported on the drill a day after its neighbors said they detected multiple ballistic missile launches and accused the North of carrying out provocations. The tests came just hours before South Korean President Lee Jae Myung departed for China for a summit with President Xi Jinping.

The official Korean Central News Agency said Sunday`s drill involving a hypersonic weapon system was meant to examine its readiness, enhance missile troops` firepower operational skills and evaluate operational capabilities of the country`s war deterrent.

"Through today`s launching drill, we can confirm that a very important technology task for national defense has been carried out," Kim said, according to KCNA. "We must continuously upgrade the military means, especially offensive weapon systems."

The possession of a functioning hypersonic weapon would give North Korea an ability to penetrate the U.S. and South Korea`s missile defense shields. In past years, North Korea has performed a series of tests to acquire it, but many foreign experts question whether the tested missiles have achieved their desired speed and maneuverability during flights.

In recent weeks, North Korea test-fired what it called long-range strategic cruise missiles and new anti-air missiles and released photos showing apparent progress in the construction of its first nuclear-powered submarine.

Observers say North Korea aims to demonstrate or review its achievements in the weapons development sector ahead of the ruling Workers` Party congress, the first of its kind in five years. Keen attention is on whether Kim would use the congress to set a new approach to relations with the U.S. and resume long-dormant talks.

North Korea`s nuclear program is expected to be discussed when Lee and Xi meet for a summit later Monday. Lee`s office earlier said he would call for China, North Korea`s major ally and economic pipeline, to take "a constructive role" in efforts to promote peace on the Korean Peninsula.

The latest launches followed Saturday`s audacious U.S. military operation that ousted Venezuelan leader Nicolás Maduro from power and brought him to the U.S. to face narco-terrorism conspiracy charges. North Korea slammed the operation, saying it again shows "the rogue and brutal nature of the U.S."

Many experts say the U.S. operation will most likely leave Kim pushing to further expand his nuclear weapons capabilities that he thinks guarantee the survival of his government and state sovereignty in the face of U.S.-led hostilities.

During Sunday`s launch drill, Kim defended his push for a stronger nuclear program. "Why it is necessary is exemplified by the recent geopolitical crisis and complicated international events," he said.