'Very dangerous challenge' if Trump calls Kim 'Rocket Man' again: North Korea

Should US President Donald Trump call North Korean leader Kim Jong Un "Rocket Man" again, that would represent a "very dangerous challenge" reminiscent of two years ago, a senior North Korean official warned on Thursday.

Choe Son Hui, who was quoted by state-run KCNA news agency, was referring to a time when tensions between when Washington and Pyongyang ran high.

Trump said on Tuesday he still had confidence in the North Korean leader but noted that Kim "likes sending rockets up".

"...That's why I call him Rocket Man," Trump told reporters at a NATO meeting in London.

Breaking a month-long lull in missile tests, North Korea fired two short range projectiles into the sea off its east coast last week in what appeared to be the latest try out of its new multiple rocket launchers, South Korea's military said.

The test-firing came as the clock ticks down on the year-end deadline that Pyongyang had given the United States to show flexibility in their stalled denuclearisation talks.

It also coincided with the US Thanksgiving holiday and took place one day before the second anniversary of the North's test of an intercontinental ballistic missile (ICBM) capable of hitting the US mainland.

US Special Representative for North Korea Stephen Biegun said the year-end deadline was an artificial one, but could mean a return to "provocative" steps that preceded the past two years of diplomacy.

US President Donald Trump, who is seeking re-election next year, has repeatedly pointed to Kim's suspension of long-range missile and nuclear bomb tests as a major achievement of his engagement with North Korea.