(CNN) North Korea conducted its second missile test within a week, sending a medium-range ballistic missile into the waters off its east coast Sunday, according to statements from North Korea and other governments.

North Korean leader Kim Jong Un supervised the test fire of the ground-to-ground strategic ballistic missile Pukguksong-2, state news agency KCNA reported. The report was issued Monday local time and does not state when the missile test took place.

"The Supreme Leader issued an order to launch the missile at the observation post," KCNA reports. "Together with officials, he analyzed the results of the test launch and expressed his great satisfaction over them, saying it is perfect."

Kim said the test showed the missile is ready for deployment and mass production, according to KCNA.

North Korean leader Kim Jong Un said the test showed the Pukguksong-2 missile is ready for deployment.

North Korean leader Kim Jong Un said the test showed the Pukguksong-2 missile is ready for deployment.

"The Supreme Leader issued an order to launch the missile at the observation post. Together with officials, he analyzed the results of the test launch and expressed his great satisfaction over them, saying it is perfect," the Korean Central News Agency reported.

"The Supreme Leader issued an order to launch the missile at the observation post. Together with officials, he analyzed the results of the test launch and expressed his great satisfaction over them, saying it is perfect," the Korean Central News Agency reported.

A North Korean Pukguksong-2 missile lifts off from a mobile launcher on Sunday, May 21.

A North Korean Pukguksong-2 missile lifts off from a mobile launcher on Sunday, May 21.

South Korea, which on Sunday had called the launch "reckless and irresponsible," said Monday the launched showed progress in the North's missile program.

"South Korean and U.S. intelligence authorities assess that North Korea, through its missile launch yesterday, has secured meaningful data for improving the credibility of its missile technology," said Roh Jae-cheon, spokesman for South Korea's Joint Chiefs of Staff.

The Pukguksong-2 is a land-based version of North Korea's main submarine-launched missile. First tested in February, it uses solid rocket fuel.

Solid fuel is like an explosive jelly, and less corrosive than liquid fuel, meaning it can be easily stored in the rocket's fuel tank, unlike the liquid alternative, which requires specially lined tanks.

Solid fuel-powered missiles need much less infrastructure, making them difficult for those monitoring North Korea's military movements to spot, as there are fewer indicators, such as movement of trucks, for South Korean or US satellites and other surveillance to pick up on.

A missile believed to be the Pukguksong-2, a land-based variant of the Pukguksong-1.

South Korea said the missile flew about 500 kilometers (300 miles) from an area near Pukchang, in western North Korea.

Japanese Defense Minister Tomomi Inada said the missile hit the water about 350 kilometers (217 miles) from the east coast of North Korea. She said the missile did not go higher than 1,000 kilometers (620 miles), according to preliminary data.

Altitude was key to the test a week earlier, which analysts called North Korea's most successful ever in its quest to develop ballistic missiles that can carry nuclear warheads.

The May 14 test reached an altitude of more than 2,100 kilometers (1,300 miles), according to North Korea. Analysts said that test gave North Korea critical information on developing a re-entry vehicle for nuclear warheads and showed Pyongyang had a missile capable of striking the US territory of Guam.

Analysts say North Korea's tests may be providing information that will bring it closer to its goal of developing an intercontinental ballistic missile that could possibly threaten the US mainland.

After the May 14 test, Melissa Hanham, senior research associate at the James Martin Center for Nonproliferation Studies in California, said it could be a stepping stone to a longer-range weapon.

"This may become half or a third of an ICBM," she said, pointing out that such missiles are built in two or three stages stacked atop of each other.

The tests on back-to-back weekends come after the May 9 inauguration of new South Korean President Moon Jae-in, who had called for a dialogue with Pyongyang over nuclear issues.

"The repeated provocation is a reckless and irresponsible behavior, like pouring cold water on the wishes of our new government and the international community for denuclearization and peace to prevail in the Korean Peninsula," said a statement from South Korea's Foreign Ministry.

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Japanese Prime Minister Shinzo Abe condemned the launch, saying the "repeated provocative acts by North Korea are totally unacceptable."

But North Korea has said its missile testing is in reaction to threats against it by the South, the US and Japan.

Pyongyang's official Korean Central News Agency said the May 14 test showed North Korea "has all powerful means for retaliatory strike" should Washington take any military action to stop its nuclear weapons program.

And Sunday's test comes just days after the US Navy said the aircraft carrier USS Ronald Reagan would soon be off the Korean Peninsula , where the carrier USS Carl Vinson is currently operating.

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Each of the Nimitz-class carriers comes with a complement of more than 60 aircraft. The carriers also sail with escorts, including guided-missile cruisers and destroyers carrying Tomahawk cruise missiles.

The Vinson and its escorts have been conducting drills with South Korean and Japanese ships since it arrived off the Korean Peninsula in late April.

China, North Korea's longtime ally, has called on both Pyongyang and Washington to make concessions to ease tensions. China says North Korea should stop its pursuit of nuclear missiles and the US should stop the war games on and around the Korean Peninsula.