The drills are taking place about 125km (77 miles) south of the disputed maritime border between the two Koreas, about 40km off the Korean coast.

The US aircraft carrier the USS George Washington and four other US navy vessels are being joined by the RoK destroyers, patrol vessels, frigates, support ships and anti-submarine aircraft.

The US says they are defensive exercises designed to deter the Democratic People’s Republic of Korea (DPRK) from launching further attacks across its border with the RoK.

DPRK shelling of a RoK island last week left two marines and two civilians dead.

The DPRK has condemned the exercises as a provocation and China has also expressed concern about military activity by foreign navies so close to its territory, and has warned the Americans not to stray too close.