North Korea warns of 'catastrophic consequences'

South Korea and the United States wrapped up their annual large-scale military drills on Sunday but continued a separate joint naval exercise that has triggered the threat of nuclear war from North Korea.  

The USS Carl Vinson aircraft carrier group arrived in waters near the Korean peninsula and began exercises with the South Korean navy late on Saturday. The South Korean navy declined to say when the exercises would be completed.

North Korea has threatened to sink the American armada.

Tensions on the Korean peninsula have been running sky-high for weeks, with signs the North might be preparing a sixth nuclear weapon test - and with Washington refusing to rule out a military strike in response.