South Korea has carried out a simulated attack on North Korea’s nuclear test site in a huge show of force in response to Pyongyang’s detonation of what it claims is a hydrogen bomb.

Seoul has also approved the complete deployment of a US anti-missile system in another sign that it intends to address North Korean provocations with reminders of its own military firepower, while keeping the door open to dialogue.

South Korean intelligence officials said there were indications that the North was preparing to test fire another ballistic missile, though they did not say when they believed the launches would take place.

The army and air force drills, held at an undisclosed location on Monday morning, involved launching ballistic missiles in a simulated strike against North Korea’s Punggye-ri nuclear test site – the scene of Sunday’s controlled detonation of what Pyongyang claimed was a powerful hydrogen bomb capable of being loaded on to an intercontinental ballistic missile.