US warns North Korea it will strike back if threatened

The US has said North Korea's missile launch was a "dark day" for the world and warned it was ready to use military force in self-defence against the rogue state.

Kim Jong-un's despotic state announced it had successfully tested a long-range missile for the first time on July 4th in a launch it said was to mark America's Independence Day.

Its leaders have insisted they will continue test launches in moves that are bringing them closer to having a functional nuclear weapon.

Nikki Haley, the US ambassador to the UN, warned that the launch had made the world a less safe place at a meeting of the security council dominated by North Korea concerns.

Ms Haley said the North Korean actions were a "clear and sharp military escalation" as she warned that America would use military force in response if it or its allies were threatened.

"The US is prepared to use the full range of our capabilities to defend ourselves and our allies," she said.

"One of our capabilities lies with our considerable military forces. We will use them, if we must."

She also hit out at China, which has provided an economic lifeline to Pyongyang, saying that it risks its trade relationship with the US if it violates international sanctions against North Korea.

Kim Jong-un has indicated he will continue developing missiles. Credit: AP

World leaders are discussing imposing fresh economic sanctions on North Korea in an effort to force it to comply with demands it give up its nuclear programme.

So far such actions have left the isolated nation bitterly impoverished by unbowed.

The UK ambassador the UN today said Britain supports imposing new binding measures to further raise the stakes for Pyongyang.

Ms Haley said that much of the responsibility for success of failure now lies with China, which represents some 90% of the North's economic trade.