WASHINGTON -- The US special representative for North Korea has condemned Pyongyang's recent missile launch but stressed readiness for "serious and sustained diplomacy" with the recalcitrant regime, the State Department said Tuesday.

Ambassador Sung Kim made the remarks during phone talks with his Japanese and South Korean counterparts -- Funakoshi Takehiro and Noh Kyu-duk-- respectively, on Saturday and Sunday (Washington time) following the North's test-firing of what it calls the Hwasong 12-type intermediate- and long-range ballistic missile.

"Special Representative Kim condemned the DPRK's ballistic missile launches as violations of UN Security Council resolutions and destabilizing to the region," State Department spokesperson Ned Price said in a release. DPRK refers to the North's official name, Democratic People's Republic of Korea.

"Special Representative Kim underscored the United States' continued readiness to engage in serious and sustained diplomacy with the DPRK in order to make tangible progress," he added.

In the calls, Kim also reaffirmed the "US commitment to the complete denuclearization of the Korean Peninsula and our ironclad commitment" to the defense of South Korea and Japan, the spokesperson said.

The North's latest missile launch on Sunday (Korea time) marks the North's seventh show of force this year and by far its biggest weapons test since the test-firing of its self-proclaimed intercontinental ballistic missile (ICBM) in November 2017. (Yonhap)