North Korea successfully carried out tests of a new long-range cruise missile over the weekend, state-run media said Monday, sparking fears that the closed country has been trying to master technology to load a nuclear weapon on the hard-to-intercept projectile.

By launching a cruise missile capable of reaching Japan, a close U.S. ally, North Korea may be watching how President Joe Biden will react, with Washington concentrating on the evolving situation in Afghanistan, a diplomatic source said.

Combined photo delivered Sept. 13, 2021, by the Korean Central News Agency shows what are described as new long-range cruise missiles being test-fired on Sept. 11 and 12, 2021. (KCNA/Kyodo)

A number of missiles newly developed by the Academy of Defense Science flew for just over two hours above the territorial land and waters of North Korea before hitting targets 1,500 kilometers away, according to the official Korean Central News Agency.

The weekend tests, which followed North Korea's staging of a military parade last Thursday in Pyongyang on the 73rd anniversary of the nation's founding, are also believed to have been aimed at generating national unity, some foreign affairs analysts say.

Unlike ballistic missiles, cruise missile launches are not targeted by U.N. Security Council resolutions.

But Japanese Chief Cabinet Secretary Katsunobu Kato said at a press conference in Tokyo on Monday that North Korea's move "would jeopardize regional peace and security."

Over the North Korean issue, senior diplomats from Japan, the United States and South Korea are scheduled to meet in Tokyo on Tuesday to discuss ways to resume denuclearization negotiations between Washington and Pyongyang.

Pak Jong Chon, a close aide to North Korean leader Kim Jong Un, observed the missile test, the news agency said. He was reportedly promoted to the Politburo of the Central Committee of the ruling Workers' Party of Korea earlier this month.

"The efficiency and practicality of the weapon system operation was confirmed to be excellent," KCNA said, adding that development has been pushed forward for the past two years.

Pak was quoted by the news agency as saying, "This is another great manifestation of the tremendous capabilities of the defense science and technology and the munitions industry of our country."

The U.S. Indo-Pacific Command said in a statement, "We will continue to monitor the situation and are consulting closely with our allies and partners," including South Korea and Japan.

The latest activity highlights North Korea's "continuing focus on developing its military program and the threats that poses to its neighbors and the international community," the command said.

Later Monday, the Rodong Sinmun, the ruling party's newspaper, ran photos of North Korea's new cruise missile that could even reach Tokyo, following what appears to be the nation's first missile test since late March.

A defense expert said it would be difficult to detect a cruise missile approaching at low altitude if it is suddenly launched. Japan's missile defense system designed to intercept ballistic missiles is also considered incapable of stopping a cruise missile.

If North Korea was attempting to carry a nuclear warhead on a cruise missile, Japan would face a serious security challenge. Tokyo is keeping a close eye on how Pyongyang will manage the new missile technology down the road.

In March, North Korea said it test-fired new tactical guided projectiles suspected to be ballistic missiles, as Biden has warned that necessary action could be taken against Pyongyang if it ratchets up tensions.

At the first congress of the ruling party to be held in January in nearly five years, Kim pledged to strengthen North Korea's military capacities and bolster its nuclear arsenal to protect national security.

The missile tests on Saturday and Sunday, meanwhile, were conducted at a time when North Korea has been struggling to cope with its worst food crisis in more than a decade.

Talks with the United States over denuclearization and sanctions relief have been stalled for around two years.

Kim said in June that the food situation in North Korea was "getting tense" as its agricultural sector was devastated by powerful typhoons and flooding in 2020.

The nuclear-armed country also seems not to have imported food products recently from China, which is known as its closest and most influential ally in economic terms, as it has blocked the border with its neighbor amid the novel coronavirus pandemic.

Pyongyang has cut off land traffic to and from China and Russia since early last year to prevent the intrusion of the virus, first detected in China's central city of Wuhan in late 2019.

North Korea claims the coronavirus that causes COVID-19 has not made inroads into the nation.

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