North Korea says it would use its “nuclear deterrent” in response to joint US-South Korean military exercises this weekend. Pyongyang was ready to launch a “retaliatory sacred war”, the state-run Korean Central News Agency (KINA) said, quoting defence officials.Washington and Seoul say the war games were to deter North Korean aggression. Tensions between the two Koreas have been high since the sinking of a South Korean warship in March. An international investigation said the ship was sunk by a North Korean torpedo, a claim strongly denied by Pyongyang.