POCHEON, Gyeonggi Province -- The exercise began with a bang from explosives being fired off near a ditch. Taking it as a cue for the North Korean Army’s hypothetical invasion, South Korea’s K-9 and K-55 self-propelled guns, as well as multiple rocket launchers, fired off dozens of volleys toward mock targets.

The artillery attack was immediately followed by multiple sorties of F-15K and FA-50 jet fighters, which scrambled from the east and dropped bombs on dummy targets designed as North Korea’s missile sites hidden in the mountain.

That was a part of joint live-fire exercise by South Korean and US armed forces that took place from April 13 through Wednesday at a training field in Pocheon, some 30 kilometers south of the Demilitarized Zone dividing the two Koreas, which are technically still at war.

It is a routine exercise that takes place almost every two years, but this year’s was particularly significant because it coincided with North Korea’s own massive artillery drill held Tuesday and Wednesday to mark the 85th anniversary of the founding of the Korean People’s Army.

“This is simulating how things would be if we did go to combat with North Korea. This is what it would look like -- us and (the) ROK army working together,” 1st Lt. Steve Porter, who served at the 366 armor regimen within the 2nd Infantry Division in Korea, told The Korea Herald.

Starting with North Korea’s invasion, the exercise scenario includes a “counterfire drill” that aims to target hundreds of North Korea’s long-range artillery unit lined up on the DMZ. Their projectile is said to reach up to Seoul’s metropolitan area, home to around 25 million South Korean people -- half of the country’s population.

Wednesday’s exercise was observed from a distance by acting President Hwang Kyo-ahn, leading presidential candidate Moon Jae-in, dozens of high-profile defense officials and army generals, and thousands of local residents.

Employing about 2,000 troops and 250 equipment from South Korea’s Army, Air Force and the US Army, the combined exercise showcased the allies’ capability to fend off North Korea in the event of an all-out war.

“I think today’s exercise can give reassurance to the people that our military has capability to neutralize North Korea’s military provocation,” Moon told reporters after the drill. “I think there are no politics when it comes to national security.”

Besides the self-propelled guns and jet fighters, the drill involved armored vehicles and tanks, such as South Korea’s K2 Black Panther and K12A tanks, as well as the US M1A2 Abrams tanks, Bradley fighting vehicles and a multiple rocket launcher system.

Among those being showcased, the most popular were arguably the AH-64E Apache helicopters, which South Korea completed deployment in January. Currently, South Korea has established two Apache battalions and underwent the fielding process, such as training pilot and outfitting the weapons.

“It’s like riding a first-class sedan. It feels so comfortable,” said a South Korean Apache pilot, who declined to reveal his identity due to the sensitivity of the issue. “I think it’s much more advanced than any other helicopters I have flown.”

The drill has taken place a total of eight times since 1977. This year’s exercise was expected to take place in August, as the previous one had two years ago, but the schedule was moved up amid heightened tension on the peninsula over North Korea’s nuclear and missile threat.

Although North Korea has yet to conduct its sixth nuclear test, Pyongyang staged a massive artillery drill Wednesday near Wonsan along the country’s eastern coast. According to the state-run Central News Agency, Pyongyang’s leader Kim Jong-un oversaw the drill.

“Today’s exercise gives an opportunity to enhance combined and joint operation capability,” said Army Lt. Col Chung Seong-ho, who served as commander of South Korea’s Army artillery battalion. “Based on the robust Korea-US alliance, we will defend our country.”

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