Pyongyang said it would put two US tourists on trial for committing crimes against the state.
North Korea breached the UN resolutions against the use of ballistic missile technology by the country.
China has used various diplomatic channels to warn North Korea against a fourth nuclear test.
The US said it was watching the Korean peninsula after reports that North Korea may be planning nuclear tests.
The North Korean embassy complained after a UK hair salon used a photo of its leader's hair.
North Korea’s recent ballistic missile launch is viewed as a violation of UN resolutions.