The operation comes after US President Donald Trump threatened to "totally destroy" North Korea
As US President Donald Trump threatened to “totally destroy” North Korea, United States and South Korean forces prepared to conduct a four-day military exercise close to the Korean border.
Troops from the 2nd Infantry Division of the US Eighth Army, the country's major ground combat unit on the Korean Peninsula, are currently participating in the "Warrior Strike" operation.
The operation is said to be part of a long-planned, regular series of joint drills – and is not viewed as a response to the latest tensions.
However, those taking part are fully aware of the current situation and their proximity to it.
Based immediately south of the Korean Peninsula's demilitarised zone (DMZ); the soldiers would fight on the front lines of any conflict here.
"None of us are oblivious to the tensions that are taking place," said Lt Col Robert Kimmel, Commander of 8th Brigade Engineer Battalion, 2nd Armoured Brigade Combat Team.
"We hear about them every day in the news, we're all aware of that, and I think given our proximity, given our partners, it does increase our urgency.
"We take it a little bit more seriously than you might if it was just a made-up scenario."
The live fire exercise involved US marines, army and air forces, along with their South Korean counterparts, targeting an imaginary enemy attacking from the mountains to the north.
F16 fighter jets could likely be seen, and heard, from the North Korean side of the border - around 20 miles away.
Pyongyang routinely describes these drills as acts of aggression and rehearsal for invasion.
China and Russia have called for them to be suspended, in return for the suspension of the North's nuclear and missile programmes - a proposal dismissed by the US ambassador to the UN as "insulting."
Japan meanwhile, has deployed a missile interceptor near the flight path of the two North Korean missiles which flew over the country in recent weeks.