WASHINGTON -- The United States government finds it "disappointing" that North Korea continues to prioritize its weapons development, a senior US official said Saturday, calling on the communist state to return to denuclearization negotiations.

The official, while speaking on condition of anonymity, said the US remains committed to the countries' denuclearization agreement signed by US President Donald Trump and North Korean leader Kim Jong-un in their first bilateral summit held in Singapore in June 2018.

"It is disappointing to see the DPRK continuing to prioritize its prohibited nuclear and ballistic missile program," the official told Yonhap News Agency.

"The United States remains guided by the vision President Trump and Chairman Kim set forth in Singapore and calls on the DPRK to engage in sustained and substantive negotiations to achieve complete denuclearization," he added, referring to North Korea by its official name, the Democratic People's Republic of Korea.

The remarks came hours after the communist state staged a massive military parade, showcasing a new intercontinental ballistic missile that is believed to be its largest so far.

John Supple, a spokesperson for the US Department of Defense, said the US was analyzing the event in consultation with its Asian allies.

"We are aware of reports related to the parade. Our analysis is ongoing and we are consulting with our Allies in the region," he told Yonhap.

The North's newly disclosed ICBM was carried on a transporter erector launcher (TEL) with 22 wheels, indicating it is longer than any of the previous long-range missiles.

"Such a massive road-mobile missile -- likely the biggest such missile on the planet -- would have the capability to add either increased range or be able to carry a bigger payload," said Harry Kazianis, senior director of Korean studies at a Washington-based policy think tank, the Institute for the National Interest.

In a midnight speech marking the 75th founding anniversary of the North's ruling Workers' Party, North Korean leader Kim Jong-un said his country will never use its defense capabilities "as a means for preemptive strike," but that it will continue to build up its war deterrent.

"But, if, and if, any forces infringe upon the security of our state and attempt to have recourse to military force against us, I will enlist all our most powerful offensive strength in advance to punish them," he added.

Kim made no mention of the United States, which is traditionally a key topic of any major speech given by a North Korean leader.(Yonhap)