The US has joined condemnation of North Korea after it tested what it says is a more advanced nuclear weapon.
President Donald Trump tweeted that North Korea's "words and actions" were "very hostile and dangerous".
North Korea has defied UN sanctions and international pressure to develop nuclear weapons and test missiles that could potentially reach the US.
South Korea, Japan, China, Russia and the UK are among those to have voiced strong criticism of the North's sixth nuclear test.
The UN Security Council is to hold an emergency meeting on Monday to discuss an international response, according to the US mission.