The bi-annual maritime drill for the defense of Dokdo Island has been resumed after being postposted in the first half of this year.
South Korea's Navy said the Marine Corps, Air Force and the Coast Guard are also participating in this drill that will last until Monday.
This comes four days after the South Korean government announced that it would not renew its military-information sharing agreement with Japan.
The defense exercise, which was originally scheduled for June, was postponed due to concerns that it might worsen the country's relationship with Tokyo.
The government first mulled over resuming the drill last month, in response to Japan's export curbs on South Korea.
However, it was rescheduled in consideration of weather conditions in the East Sea and South Korea-U.S. joint military exercises slated for the second half of the year.
Analysts saw the timing of the drill's resumption as an attempt to maintain strategic ambiguity.
The size of the exercise has also grown compared to the previous year according to a military official.
A 7,600 ton class Aegis-equipped destroyer as well as the ROK Navy's Task Flotilla Seven and special forces are taking part in this exercise for the first time.
Founded in 2010, Task Force Flotilla Seven is the Navy's premier formation that consists of three Aegis destroyers and six other warships.
Some analysts say that the strengthened drill is also an effort to keep China and Russia in check, with the two countries ramping up their military activities around the Korean Peninsula in recent months.
In consideration of the drill's significance and size, the military named it the 'East Sea territory defense exercise,' reflecting its determination to defend the country's territories in the East Sea.
Hong Yoo, Arirang News.