WASHINGTON -- North Korea's two most recent missile launches were aimed at testing a new intercontinental ballistic missile (ICBM) system ahead of a possible full-fledged ICBM test, a senior US official said Thursday, adding the US plans to take action that will hinder Pyongyang's nuclear and missile programs.

North Korea earlier confirmed launching missiles on Feb. 27 and Saturday (Seoul time), claiming they were aimed at developing a reconnaissance satellite.

"After careful analysis, the US government has concluded that the DPRK's two ballistic missile tests on February 26, March 4 (US time) of this year involved a relatively new intercontinental ballistic missile system," the US administration official said in a telephonic press briefing, referring to North Korea by its official name, the Democratic People's Republic of Korea.

The official, who spoke on condition of anonymity, said the new ICBM was first unveiled during a 2020 parade in Pyongyang.

Pyongyang had showcased its new ICBM, Hwasong-17, during a parade that marked the 75th anniversary of the founding of the ruling Workers' Party on October 10, 2020,

Experts have since noted the Hwasong-17 was mounted on a transporter erector launcher (TEL) with 22 wheels, compared with a 18-wheel TEL used to transport the Hwasong-15 ICBM, a possible indication that it may have a longer range than previous models.

The US official said the North's latest missile tests did not demonstrate the range or capability of an ICBM.

"These launches are likely intended to test elements of this new system before the DPRK conducts a launch at full range, which they will potentially attempt to disguise as a space launch," said the official.

The South Korean Joint Chiefs of Staff earlier said the North Korean missile launched on February 27 flew about 300 kilometers at a maximum altitude of 620 km, and that the missile fired Saturday flew 270 km at a top altitude of 560 km.

North Korea reported on Thursday (Seoul time) that leader Kim Jong-un had visited the country's space agency and commended recent efforts to develop a reconnaissance satellite.

On Friday (Seoul time), the North said Kim also visited a satellite test site on the west coast that is said to be capable of launching ICBMs.

North Korea has maintained a self-imposed moratorium on nuclear and long-range missile testing since late 2017, but said in January that it may consider restarting "all temporarily-suspended activities" amid a stalemate in dialogue with the US.

John Kirby, press secretary of the US Department of Defense, said the US normally does not disclose details of North Korean missile launches, but decided to do so "because we believe that the international community must speak in a united voice to oppose the further development and proliferation of such weapons by the DPRK."

"While the United States remains committed to a diplomatic approach, we will continue to take all necessary measures to ensure the security of the United States and our allies," he added.

US Indo-Pacific Command on Thursday said it has intensified intelligence, surveillance and reconnaissance collection activities around the Korean Peninsula as of Monday.

The US administration official, who spoke on condition of anonymity, underlined the US' commitment to dialogue with the North, noting that President Biden also remains open to meeting with Kim.

"We continue to seek diplomacy and we are prepared to meet without preconditions," he said.

"President Biden himself has previously made clear that he is open to meeting with Kim Jong-un when there is a serious agreement on the table, which will need to be based on working-level negotiations because, as we saw in the past administration, leader-level summits alone are no guarantee of progress," added the official.

Kim held two historic summit meetings with former US President Donald Trump, but has stayed away from denuclearization talks since their second summit in Hanoi in February 2019 ended without a deal.

The US Department of Treasury will announce a set of new steps Friday that will help prevent North Korea from "accessing foreign items and technology that enable it to advance prohibited weapons programs," the US administration official said.

"The United States strongly condemns the DPRK for these tests. The launches are a brazen violation of multiple United Nations Security Council resolutions, needlessly raise tensions and risk destabilizing the security situation in the region," he added.

In addition to the two suspected ICBM tests on Saturday and Feb. 27, the North staged seven rounds of missile launches in January, marking the largest number of missile tests it conducted in a single month. (Yonhap)