N. Korea says missile test aimed at testing carrying large nuclear warhead

North Korea said on Monday it had successfully conducted a newly developed mid-to-long range missile test on Sunday supervised by leader Kim Jong Un and aimed at verifying the capability to carry a "large scale heavy nuclear warhead."

Kim warned the United States should not misjudge the reality that its mainland is in the North's "sighting range for strike," the North's official KCNA news agency reported.

The North fired a ballistic missile that landed in the sea near Russia on Sunday in a launch that Washington called a message to South Korea, days after its new president took office pledging to engage Pyongyang in dialogue.

The missile was launched at the highest angle so as not to affect the security of neighbouring countries and flew 787 kilometres, reaching an altitude of 2,111.5 kilometers, KCNA said.

"The test-fire aimed at verifying the tactical and technological specifications of the newly developed ballistic rocket capable of carrying a large-size heavy nuclear warhead," KCNA said.

North Korea is believed to be developing an intercontinental ballistic missile (ICBM) capable of carrying a nuclear warhead and reaching the mainland United States.

The US military's Pacific Command said the type of missile that was fired was "not consistent with an intercontinental ballistic missile."

The United Nations Security Council is due to meet on Tuesday to discuss North Korea's latest missile launch, diplomats said on Sunday, which was requested by the United States and allies South Korea and Japan.

US Ambassador to the United Nations Nikki Haley called the launch a message by Pyongyang to South Korea after the election of President Moon Jae-in, who took office on Wednesday.

"You first have to get into Kim Jong Un's head -- which is, he's in a state of paranoia, he's incredibly concerned about anything and everything around him," Haley told ABC's "This Week" programme, referring to North Korea's leader.

The report on the missile's flight was largely consistent with South Korean and Japanese assessments on Sunday that it flew 700 km and reached an altitude of more than 2,000 km, which is further and higher than an intermediate-range missile tested in February from the same region, northwest of Pyongyang.

"North Korea's latest successful missile test represents a level of performance never before seen from a North Korean missile," Washington-based monitoring project, 38 North, said in an analysis issued on Sunday.

"It appears to have not only demonstrated an intermediate-range ballistic missile (IRBM) that might enable them to reliably strike the US base at Guam, but more importantly, may represent a substantial advance to developing an intercontinental ballistic missile (ICBM)," it said.