by Beti Gebeyehu / 3,899 Views
The US has said its policy of "strategic patience" with North Korea is over and suggested it might decide to take pre-emptive military action.
Secretary of State Rex Tillerson said the option was "on the table" if the threat from the North's weapons programme reached a level requiring it.
During a visit to South Korea, he also said the US was exploring a range of new diplomatic and economic measures.
And he defended the deployment of a US missile system in South Korea.
The move has angered China but South Korea and the US say the system is needed to defend against North Korea.
US President Donald Trump tweeted that North Korea was "behaving very badly" and had been "playing" the US "for years". "China has done little to help!" he added.
Mr Tillerson spoke shortly after visiting the demilitarised zone which divides the two Koreas.
He arrived in South Korea from Japan, where he had said that 20 years of efforts aimed at persuading North Korea to abandon its nuclear ambitions had failed. Read more