North Korea's missile programme is progressing faster than expected, South Korea's defence minister said on Tuesday, after the U.N. Security Council condemned the weekend launch of a new long-range missile and demanded Pyongyang halt weapons tests.

Han Min-koo told South Korea's parliament that Sunday's test had been detected by the controversial U.S. THAAD anti-missile system, which was deployed in South Korea last month, infuriating China.

North Korea has defied all calls to rein in its nuclear and missile programs, even from China, its lone major ally, calling them legitimate self-defence.

It has been working to develop a nuclear-tipped missile capable of striking the U.S. mainland, and experts say Sunday's test was another step toward that aim.

U.S. President Donald Trump's administration has called for an immediate halt to North Korea's missile and nuclear tests, and U.S. Disarmament Ambassador Robert Wood said on Tuesday that China's leverage was key and Beijing could do more.

The U.S. ambassador the United Nations, Nikki Haley, said the United States believed it could persuade China to impose new U.N. sanctions on North Korea and warned that Washington would "call out" states supporting Pyongyang and target them with sanctions too.

Speaking to reporters ahead of a closed-door meeting of the 15-member U.N. Security Council on the missile launch, Haley made clear that Washington would only talk to North Korea once it halted its nuclear programme.

The United States has been discussing possible new U.N. sanctions with China since North Korea's previous missile test about two weeks ago.

"The conversations that I have had ... in dealing with Beijing is that if (North Korea) did something else and if it looked to be long-range, which this does, and if it looks like it is proactively leaning toward an ICBM, which it does, then we would take action," Haley said.

"I believe that China will stay true to that and we will come together on how we're going to do that," she said. "We have not seen anything from them in the past week but we are encouraging them to continue moving forward."

South Korea's Han said Sunday's test was "successful in flight."

"It is considered an IRBM (intermediate range ballistic missile) of enhanced calibre," he said, referring to a class of missile designed to travel up to 3,000 to 4,000 km (1,860 to 2,485 miles).

Asked whether North Korea's missile programme was developing faster than expected, he said: "Yes."

Han said the Terminal High Altitude Area Defense (THAAD) anti-missile system detected the missile, marking the first time it had been put to use since its deployment.

China has strongly opposed THAAD, saying it can spy into its territory, and South Korean companies have been hit in China by a nationalist backlash over the deployment.

North Korea says Sunday's launch tested the capability to carry a "large-size heavy nuclear warhead" and its ambassador in Beijing said on Monday that Pyongyang would continue such test launches "any time, any place."

A North Korean diplomat, Ju Yong Choi, told the U.N. Conference on Disarmament in Geneva on Tuesday that North Korea would "bolster its self-defence capabilities as long as the United States continues its hostile policies ... and imposes nuclear threats and makes blackmail."

New South Korean President Moon Jae-in met Matt Pottinger, overseeing Asian affairs at the U.S. National Security Council, on Tuesday and afterwards South Korea's presidential Blue House announced that Moon would meet Trump in Washington next month.


"FURTHER SANCTIONS POSSIBLE"

On Monday, the U.N. Security Council said it was vital that North Korea show "sincere commitment to denuclearisation through concrete action and stressed the importance of working to reduce tensions".

The council demanded North Korea halt its tests and said it was ready to impose further sanctions.

North Korea's foreign ministry rejected the statement, saying it infringed on its right to self-defence, particularly as the missile was fired at a sharp angle to ensure the safety of neighbouring countries.

U.S. Disarmament Ambassador Wood said China was key given that 90 percent of North Korea's trade was with that country. "Clearly, there is a lot more leverage that China has, and we would like China to use," he said.

The Security Council first imposed sanctions on North Korea in 2006 and has stiffened them in response to its five nuclear tests and two long-range rocket launches. Pyongyang is threatening a sixth nuclear test.

Trump warned in an interview with Reuters this month that a "major, major conflict" with North Korea was possible, and in a show of force, sent the Carl Vinson aircraft carrier strike group to Korean waters to conduct drills with South Korea and Japan.

Another carrier, the Ronald Reagan, left Yokosuka in Japan on Tuesday on its regular spring patrol, which would last three to four months, a spokesman for the U.S. Seventh Fleet said.

Besides worries about North Korea's missile and nuclear weapons programs, cyber security researchers have found technical evidence they said could link Pyongyang with the WannaCry "ransomware" cyber attack that has infected more than 300,000 computers in 150 countries since Friday.