ISTANBUL

South Korea, the US and Japan held three-day joint naval drills on the Korean Peninsula, as North Korea has suggested it would re-define its ties with Seoul, calling it a “principal enemy.”

The South’s Joint Chiefs of Staff said the drills, involving nine warships off Jeju Island, had been held since Monday in waters south of the Peninsula, Seoul-based Yonhap News reported on Wednesday.

This comes after Pyongyang on Sunday tested a solid-fuel intermediate-range ballistic missile carrying a hypersonic warhead into the East Sea, in its first missile launch this year.

North Korea said the missile test had "nothing to do with the regional situation."

The nuclear-powered aircraft carrier USS Carl Vinson also took part in the trilateral naval exercise.

South Korea’s military said: "The exercise is aimed at bolstering the three nations' deterrence and response capabilities against North Korea's nuclear and missile threat as well as maritime threats.”

Seoul on Wednesday also imposed sanctions on 11 vessels and five individuals and entities.

The targeted persons and entities are allegedly “engaged in illegal ship-to-ship transfers of oil and other products to North Korea.”

It is the first time in nearly eight years that Seoul has sanctioned ships.

Pyongyang has said it will make constitutional changes to abandon seeking reunification of the Korean Peninsula divided during the 1950s war of Koreas which ended in an armistice. Later, the US deployed around 28,500 soldiers in South Korea.

South Korean President Yoon Suk-yeol has also warned Pyongyang, saying his government “is different from any previous government.”