North Korea on Sunday successfully test fired a missile which is reportedly a new type of rocket capable of carrying a large nuclear warhead.
North boasted on Monday that the launch of a mid-to-long range missile ‘Hwasong-12’ the previous day, supervised by leader Kim Jong Un, was aimed at verifying the capability to carry a "large scale heavy nuclear warhead".
"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," North's official KCNA news agency reported.
The missile, launched at a steep angle, reached an altitude of 2,111km (1,242 miles) and travelled 787 km (489 miles), landing in the sea west of Japan, news agency said.
However, the U.S. military's Pacific Command was quoted as saying by Reuters on Sunday that the type of missile that was fired was "not consistent" with an ICBM and South Korea's military played down the North's claim of technical progress on atmospheric re-entry.
"We believe the possibility of that is low," said Roh Jae-cheon, a spokesman for South Korea's Office of the Joint Chiefs of Staff.
However, the US and Japan have called for an emergency meeting of the UN Security Council on Tuesday.