Media reports said North Korea has successfully miniaturised a nuclear warhead that can fit inside its missiles.
"President Trump believes that Kim has an unprecedented opportunity to change the trajectory of our relationship and bring peace and prosperity to his country," Pompeo said.
During the phone call, Trump underscored the determination of the US to defend itself and its allies from the growing threat posed by the North Korean regime, the White House said.
From the Syrian civil war to the Ukrainian crisis to the terror unleashed by the dreaded Islamic State, there was no lack of news in 2014. In this five-part series, rediff.com presents a selection of the year's most enduring moments year from around the world.
The US also blasted China and Russia for not joining hands with the international community in their efforts to combat the North Korean threat.
After Pyongyang tests a missile potentially capable of reaching the US, Dr Rajaram Panda explores the realistic -- and peaceful -- options before Donald Trump and the international community at large.
Sanctions against North Korea following its H-bomb test could have serious repercussions and may prove disastrous for all the players involved, says Debalina Ghoshal.
'Despite much hype of optimism, everyone went home empty-handed without a clear picture where they are heading in the future,' notes Dr Rajaram Panda.
The Korean summit, laden with symbolism in everything from the choice of location to the mango mousse for dessert, could just be the first round in a continuing dialogue, says Dr Rajaram Panda.