Donald Trump told North Korea’s leader that he would take “all necessary steps” against the state’s nuclear and missile programme.
North Korea has been ramping up its nuclear programmes and has threatened US territories which led to President Trump and Kim Jong-un’s war of words.
John Negroponte, a former US ambassador to the UN, has warned about the difficulties in solving the North Korea crisis.
Speaking to Fox Business, he said: “The problem is, the more you contemplate a military approach to this matter the more horrific or horrendous the outcome would appear to be.
“There is probably no way if it does come to blow, of avoiding some kind of retaliation from North Korea against South Korea, since the city of Seoul is so vulnerable to even conventional artillery attacks from the north.
“I think once you go down the road of a military approach to these things, the going could get very rough.”
Mr Negroponte added that the US needed to partake in “intense diplomacy” with China to put a stop to Kim Jong-un’s threat.
President Donald Trump has called on both China and Russia to help scupper the hermit kingdom’s nuclear arsenal.
North Korea’s most recent missile test took place on November 29, and the regime said the Hwasong-15 missile flew 590 miles before landing in the sea new Japan.
After the missile test Kim Jong-un declared that North Korea had “finally realised the great historic cause of completing the state nuclear force”.
The US President has now promised to “take care” of the situation as he delivered a huge warning to Kim Jong-un.
He said: “This situation should have been taken care of long before I got into office when it was much easier to handle. But it will be taken care of. We have no choice.
“We have united our allies in an unprecedented effort to isolate North Korea, however, there is much more work to do.“America and its allies will take all necessary steps to achieve a denuclearisation and ensure that this regime cannot threaten the world.”