North Korean and US leaders have fired another round of harsh words, with the North Korean regime calling Donald Trump a “lunatic old man” seeking to start a nuclear war.

The regime state media accused Mr Trump of escalating tensions between the two countries “to the extremes”, adding that “no-one can predict when the lunatic old man of the White House, lost to sense, will start a nuclear war”.

The comments come as Mr Trump met with Japanese Prime Minister Shinzo Abe at a summit in Tokyo during his first tour of Asia as President, and both leaders refused to rule out military action against the neighbouring country.

“Some people say my rhetoric is very strong but look what has happened with very weak rhetoric in the last 25 years,” said the President.

While Mr Trump called the nation “a threat to the civilised world” – as he stood in range of a North Korean ballistic missile – Mr Abe agreed that, when it came to dealing with Kim Jong-un, “all options were on the table”. He also announced new sanctions against dozens of North Koreans.

Japan does not have a standing army as part of its post-war pacifist constitution, but it has so-called "self-defence forces".

Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Show all 6 1 /6 Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Photos released by North Korea show Kim Jong-un talking to subordinates next to a device thought to be the new thermonuclear weapon. There is no way of independently verifying the pictures STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb North Korea claims it has successfully tested an advanced hydrogen bomb which could be loaded onto an intercontinental ballistic missile AFP/Getty Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A diagram on the wall behind Mr Kim shows a bomb mounted inside a cone STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb North Korean leader Kim Jong-Un (C) attending a photo session with participants of the fourth conference of active secretaries of primary organisations of the youth league of the Korean People's Army (KPA) in Pyongyang STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A new stamp issued in commemoration of the successful second test launch of the "Hwasong-14" intercontinental ballistic missile KCNA via Reuters Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A new stamp issued in commemoration of the successful second test launch of the "Hwasong-14" intercontinental ballistic missile KCNA via Reuters

Mr Abe is seeking to reverse this stance, given North Korea’s firing of missiles over the country twice in recent months. In September, North Korea also claimed it had tested a powerful hydrogen bomb.

Pyongyang has already declared Mr Trump as “deranged” in response to the President’s fiery speech at the United Nations summit in New York earlier this year.

H R McMaster calls North Korea a threat 'to the entire world'

Mr Trump called the regime leader “little rocket man” and vowed to meet any aggression with “fire and fury”, saying he would “totally destroy” the nation.

In recent months the US has also upped joint military drills with South Korea, including sailing fleets of warships and flying planes near the border, as well as practising dropping bombs on targets in South Korea.

Mr Trump tweeted in September that he was "allowing Japan and South Korea to buy a substantially increased amount of highly sophisticated military equipment from the United States."

He reiterated his vow during his stay in Japan this week, insisting that Japan would be able to shoot North Korean missiles "out of the sky" with such military equipment from the US.