People watch a TV at the Seoul Railway Station showing images of North Korea's missile launch during a news program, Jan. 31. The United States has requested an emergency meeting of the U.N. Security Council, Thursday, on North Korea, which launched its most powerful missile since 2017 last weekend, diplomatic sources said Tuesday. AP-Yonhap

The United States has requested an emergency meeting of the U.N. Security Council, Thursday, on North Korea, which launched its most powerful missile since 2017 last weekend, diplomatic sources said Tuesday.

The meeting is expected to be held behind closed doors. It is up to Russia, the president of the Security Council for the month of February, to confirm the timing.

"We really do hope that the Council will be able to speak with one voice" with a declaration, a diplomat speaking on the condition of anonymity said.

North Korea confirmed Monday it had launched a Hwasong-12 "ground-to-ground intermediate- and long-range ballistic missile," in its first test since 2017 of a weapon that powerful.

Earlier Tuesday, U.N. Secretary-General Antonio Guterres denounced the launch as "a clear violation of Security Council resolutions."

"At least what we should insist upon is that the Council would urge DPRK to respect U.N. Security Council resolutions," the anonymous diplomat added, referring to the country's official name of the Democratic People's Republic of Korea.

"If the Council is not even able to call for respect of its own decisions, we have a problem."

North Korea is "making steady progress on ballistic missiles, improving the range, the precisions and the lethality of its missiles," he said.

The country has both nuclear and ballistic missile technologies, the diplomat said.

"At some stage if you mix the two technologies, which they don't seem to have been able to manage until now...the threat will be absolutely intolerable," he said.

U.S. envoy to North Korea Sung Kim has discussed the latest launch with South Korean and Japanese authorities in recent days, State Department spokesman Ned Price said in a statement.

"Special Representative Kim condemned the DPRK's ballistic missile launches as violations of U.N. Security Council resolutions and destabilizing to the region," Price said, underscoring the U.S.'s "ironclad commitment" to help defend allies Japan and South Korea and to pursue diplomatic solutions with North Korea.

The test on Sunday was North Korea's seventh in January ― the most ever carried out by the country in a calendar month, raising fears Pyongyang could renew nuclear weapons and intercontinental ballistic missile tests.

The test broke a 2018 moratorium by Pyongyang. In 2017, the U.N. Security Council on three occasions decided unanimously to impose new heavy economic sanctions on Pyongyang for its nuclear weapons and missile tests.

The sanctions, the council's latest show of unity over North Korea, target the country's oil imports as well as its coal, iron, textile and fishing exports. (AFP)