This file image shows the disputed Dokdo (Tokto) islands, also known as the Liancourt Rocks and Takeshima in Japanese, a group of small islets in the Sea of Japan controlled by South Korea and claimed by Japan
Six warships and seven aircraft will take part in the military drills in the two-day military drills, which will begin in the Sea of Japan later on Monday.
A unit of marines will also land on the largely bare rocky islets of Doko, which have been under South Korea's control since the end of World War II in 1945.
Prior to that, not only the Dokdo islands, but also the whole Korean peninsula had been under Japanese control.
In 1945, when American and ex-Soviet forces captured the Korean peninsula, Japanese rule over Korea ended and eventually South Korea took control of Dokdo islands.
"The Dokdo defense drill is a routine training conducted to prevent an invasion from external forces," Choi Hyun-soo, a spokeswoman at Seoul's Defense Ministry, said.
Tokyo claims that the islands, which it calls Takeshima, are part of Japan and accuses Seoul of occupying them.
Reacting to South Korea's maneuvers, Japan lodged a protest with Seoul's embassy in Tokyo, describing the planned drills as "extremely deplorable" and unacceptable, the NHK news broadcaster reported.
In foreign policy, both South Korea and Japan are US allies and view North Korea as a common enemy; however, their bilateral relations remain heavily strained over historical and territorial rows.
The two neighbors are also deeply mired in a long-running feud over Japan's wartime sexual slavery of Korean women despite an agreement to settle the issue in 2015.
Korea first staged the Dokdo drills in 1986 and has conducted them twice a year since 2003.
Comment: It'll be interesting to observe Japanese support (or a lack thereof) for Korean reunification in the coming years.
There hasn't been a unified independent Korea since the 19th century, when Japan 'converted to westernism' and colonized the peninsula. Will Japan mind seeing the return of a strong Korea, and one likely aligned with Beijing? Not likely!
Sadly, this means that a 'fracture line' will remain in northeast Asia, though it'll no longer be located halfway down Korea, but in the Sea of Japan.