China and the United States will work together to try and prevent further missile tests by North Korea, US President Barack Obama says.

North Korea warns that its military is ready to attack Seoul's presidential palace unless South Korean President Park Geun-hye apologizes for "treason" and publicly executes officials responsible for what Pyongyang says are plans to attack its leadership.

North Korea fires five short-range missiles into the sea off its east coast -- the latest in a series of launches ordered by leader Kim Jong-Un amid rising military tensions.

A small artificial earthquake has been detected in North Korea, according to South Korean officials who say it was probably due to "blasting work".

The US, backed by China, submits a draft resolution to the UN Security Council aimed at imposing tougher sanctions on North Korea.

The North Korean authorities say they have successfully tested a hydrogen bomb amid reports of a tremor near the main nuclear test site.