South Korean President Yoon Suk-yeol has overseen massive live-fire drills staged jointly by South Korean and US forces, conducted on the largest scale ever, under the scenario of a North Korean invasion.

The combined joint live-fire exercise started on May 25 in a South Korean training field not far from the inter-Korean border, to mark the 70th anniversary of the South Korean-US alliance.

President Yoon observed the drills on Thursday, as the last round of drills took place.

He watched South Korean and US soldiers practice counterattacks against a possible North Korean invasion, with tanks and multiple-rocket launchers shelling at a target slope, aided by attack helicopters and fighter jets.

The South Korean government said the joint drills were conducted on the largest scale ever, involving over 600 units of weaponry, and with about 2,500 South Korean and US troops participating.

After the three-week exercise ended, President Yoon said that it was quite reassuring to watch the overwhelming military power of the South Korea-US alliance.

He expressed his resolve to protect the lives and safety of the South Korean people by maintaining solid national security arrangements and holding practical drills.