US President Donald Trump on Wednesday offered North Korean leader Kim Jong-Un what he called "a path towards a much better future" as tensions soar over Pyongyang's nuclear ambitions.

"The weapons you are acquiring are not making you safer," Trump said at the South's parliament, in what he described as a direct message for Kim. "They are putting your regime in great danger.

"Yet despite every crime you have committed against god and man," he went on, "we will offer a path towards a much better future