North Korean leader Kim Jong-un won't stop on his mission to attain a missile that can reach the US

The US has warned the screws are tightening on North Korea after the rogue nation yesterday carried out its latest missile test once again in defiance.

And as global tensions rose following Pyongyang's seventh missile launch this year, North Korean leader Kim Jong-un warned the weapons weren't the exclusive property of the US.

According to state media reports, yesterday's missile was a new type of "medium long-range" ballistic rocket that is capable of carrying a heavy nuclear warhead.

But the latest test also showed a more alarming concern.

According to The Wall Street Journal it showed just how serious North Korea was about its achieving its nuclear ambitions.

Kim has launched more major missiles in the past three years than in the three previous decades combined, the WSJ reported, adding the current leader has modernised the country's nuclear program.

He also "hugged officials in the field of rocket research, saying that they worked hard to achieve a great thing".Kim, who attended yesterday's test, described the nuclear-capable missile as a "perfect weapon system".

And while Kim's father and grandfather used the program to gain international leverage, the current North Korean leader wants to ensure the tests show the weapons can be reliably used in conflict.

'Nuclear blackmail'

Just today North Korea claimed it successfully tested a new type of rocket in its latest missile launch, while analysts said it showed an unprecedented range that brought US bases in the Pacific within reach.

Many experts warn North Korea is not yet able yet to make a nuclear warhead small enough to mount on a long-range missile, however some analysts think it can arm shorter range missiles with warheads.

Kim has already said the North would stage more nuclear and missile tests in order to perfect nuclear bombs needed to deal with US "nuclear blackmail".

North Koreans wave national flags and artificial flowers as they march next to a float with models of different missiles across Kim Il-sung Square during a military parade. Photo/AP

According to state media, Kim remained defiant about the tests and reportedly warned the US he will not be stopped.

He was quoted as saying: "the most perfect weapon systems in the world will never become the eternal exclusive property of the US while saying Washington should not disregard or misjudge the reality that its mainland and Pacific operation region are in (North Korea's) sighting range for strike."

'Tighten the screws'

UN Ambassador to the United Nations Nikki Haley yesterday said the world was fast losing patience with North Korea.

Haley warned the US and its international partners will continue to "tighten the screws" on Kim Jong-un and told ABC's This Week the North Korean leader is "in a state of paranoia".

"He's incredibly concerned about anything and everything around him," Haley said.

"What we're going to do is continue to tighten the screws. He feels it."

White House spokesman Sean Spicer also warned North Korea has been a menace for far too long.

"Let this latest provocation serve as a call for all nations to implement far stronger sanctions against North Korea," he said.

The world has become increasingly concerned about North Korea's nuclear ambitions. Photo/AP

Warning bells

Peter Hayes, an Honorary Professor at the Centre for International Security Studies at Sydney University and a leading expert on nuclear policy in the region, told news.com.au Kim Jong-un has grown the country's nuclear capabilities in recent years.

Prof Hayes said North Korea has already demonstrated nuclear weapons capabilities and tested nuclear devices underground on five occasions, including twice last year.

According to him, the DPRK is aiming to field a working missile with intermediate range.

"A long-range missile is much harder to achieve. Whereas an IRBM (intermediate-range ballistic missile) can hit Japan, Guam, Alaska, South Korea, and of course, China and Russia."

In an interview with news.com.au last month, United States Studies Centre's Alliance 21 Research Fellow Brendan Thomas-Noone, said North Korea had come further with its technology than the world thought.

Thomas-Noone, an expert in nuclear deterrence in the Indo-Pacific, also said North Korea's military parade last month showed its program has made huge leaps in missile technology.

North Korean leader Kim Jong-un appears on screen at railway station in Seoul after his country test-launched a ballistic missile that landed in the Sea of Japan. Photo/AP

Nuclear ambitions

According to Pyongyang's official Korean Central News Agency yesterday's missile was a Hwasong-12.

The missile launch raised heightened fears with South Korea, Japan and the US which said the missile flew for half an hour and reached an unusually high altitude before landing in the Sea of Japan.

Tokyo also warned the flight pattern could indicate a new type of missile altogether.

The missile flew for about 30 minutes, travelling about 800 kilometres and reached an altitude of 2000 kilometres, according to Japanese authorities.