South Korea on Monday kicked off a military exercise designed to defend its easternmost islets of Dokdo, prompting Japan to protest against the maneuver as it continues to claim sovereignty over Dokdo.

Taking place in the waters near Dokdo, the two-day exercise involves six naval vessels and seven aircrafts, according to the Navy and the Marine Corps. The exercise includes a landing drill where a marine squad sets foot on the islets. 

The military said the exercise is being conducted in a scale similar to that of last year, describing it as a “routine drill” to defend its sovereign territory. South Korea has been carrying out the joint drill twice a year since 1986, involving the Navy, Marine Corps, Air Force and the Coast Guard.

“Dokdo defense exercise is a routine military drill designed to protect the South Korean island Dokdo from invasion from outside forces,” said Choi Hyun-soo, a spokesperson from the Ministry of National Defense.

The military is expected to mobilize its naval and air assets, including the 3,200-ton Yangmanchun destroyer, P-3C maritime surveillance plane, F-15 fighter jets and UH-60 Black Hawk helicopters, defense officials said.

A squad-size Marine Corps unit landing at Dokdo to protect against hypothetical invasions is part of the drill. Stationed in the southeastern port city of Pohang, the Marine Corps‘ Quick Response Team stands ready to be dispatched anywhere in South Korea within 24 hours.

The Japanese government has delivered strong protests against the drill through diplomatic channels, denouncing the South Korean government for holding what it sees as an “unacceptable exercise.”

According to the Japanese broadcaster NHK and other media outlets, the Japanese foreign ministry officials and those working in the Japanese Embassy in Seoul strongly protested against the exercise.

Korea has maintained control of the outcrops with a small batch of coast guard officers since its liberation in 1945.

While South Korea exercises “effective control” on Dokdo, Japan has continued to make claims on the islets -- known as Takeshima in Japan.

Most recently, The Japanese annual diplomatic report -- called Diplomatic Blue Paper -- reiterated its claim on Dokdo before the document was submitted to the cabinet in Japan in May. The South Korean Foreign Ministry denounced the move, urging Japan to drop the claim.

Since there is a remote possibility of the military exercise escalating into actual skirmishes, the latest tit-for-tat appears to show strained bilateral ties over thorny issues such as history textbooks and wartime sex slavery.

Foreign Minister Kang Kyung-hwa said Monday that the government will deepen “future-oriented” relationship with Japan and coordinate with Tokyo to improve its ties with North Korea.

By Yeo Jun-suk (jasonyeo@heraldcorp.com)