North Korea has tested a new intercontinental ballistic missile system during missile launches in recent weeks, according to U.S. officials. The two tests, on Feb. 26 and March 4, involved a "relatively new intercontinental ballistic missile system," a U.S. government official said Thursday.

Neither the range nor capabilities of intercontinental ballistic missiles were shown, he said. Presumably, he said, the purpose was to "test elements of this new system" before North Korea completes a full-range launch.

"This is a serious escalation by North Korea," the U.S. government official said. As a result, the U.S. plans to impose new sanctions on the country, which is largely isolated internationally.

North Korea had spoken of preparations for a reconnaissance satellite after the tests on Feb. 26 and March 4. The U.S. government official now said that should North Korea conduct a full-scale test with the new intercontinental ballistic missile, Pyongyang is likely to misrepresent it as the launch of a space rocket. According to the report, the new system was first displayed at a military parade in October 2020.

The Japanese Defense Ministry confirmed the U.S. information. According to the report, the missile in February had reached an altitude of up to 600 kilometers and had flown about 300 kilometers. The missile in March flew up to 550 high and also 300 kilometers farther. Tokyo called the tests a "threat to peace and security that can never be tolerated."

North Korea last tested an intercontinental ballistic missile in November 2017. According to experts, the Hwasong-15 missile tested in that test can reach the entire continental United States. Subsequently, North Korea refrained from further tests of intercontinental ballistic missiles.

North Korea's strongman Kim Jong Un had recently visited the launch site of the latest suspected tests in Sohae, according to a report Friday by state news agency KCNA. During the visit, he had ordered the launch site to be upgraded and modernized.

However, a diplomatic offensive by North Korea's strongman Kim Jong Un with then-U.S. President Donald Trump failed to produce tangible results. Talks between Pyongyang and Washington have been on hold since negotiations broke down in 2019.

The international community has already imposed tough sanctions on Pyongyang because of North Korea's nuclear weapons and missile programs. Washington now wants to present new sanctions on Friday that will further restrict North Korea's access to foreign technologies, he said.

The U.S. announcement comes shortly after conservative opposition candidate Yoon Suk Yeol won the presidential election in South Korea. The 61-year-old former prosecutor general had threatened a pre-emptive strike against North Korea during the election campaign.