North Korea has claimed that the missile it tested on Sunday was a new type of rocket capable of carrying a large nuclear warhead
North Korea missile test, was launched at a steep angle, reached an altitude of 2,000km (1,242 miles) and travelled about 700km, landing in the sea west of Japan.
North Korea said on Monday it was a test of the abilities of a "newly developed ballistic rocket".
South Korea's military said it could not yet verify the North's claims, but said the North's missiles did appear to be able to leave and re-enter the atmosphere, which is crucial to developing intercontinental ballistic missiles (ICBMs), the Yonhap news agency reported.
Repeated missile tests by the North this year - not all of them successful but all a breach of UN sanctions - have sparked international alarm and raised tensions with the US.
The US and Japan have called for an emergency meeting of the UN Security Council on Tuesday.