Dozens of M1A1 Abrams tanks rumbled over the hills and dummy grenades exploded. Through the haze of smoke bombs, American soldiers scrambled to battle positions near the border with North Korea.
For many South Korean villagers near the border, the US 2nd Infantry's frontline deployment and exercises like Saturday's have been a soothing reminder of Washington's commitment to deterring hostilities on the divided peninsula.
Now that US troops say they will move further south from the Demilitarized Zone separating the two Koreas, villagers are worried they'll be left badly exposed. Others feel jittery but acknowledge it's time for the Americans to go.
"Considering South Korea's economy and military strength, I'm not confident that we can defend the 155 mile-long DMZ all by ourselves," said Kim Yong-shin, 71, at Uijongbu, a town that lies between the zone and Seoul, 60km south. "I think they should remain."
Uijongbu is home to Camp Red Cloud, headquarters of the 2nd Infantry Division.
Like Kim, who runs a tailor shop near the base, many townspeople earn their living catering to the soldiers. Bars and barber shops advertise their services with English signboards. American soldiers and their camouflaged vehicles are so familiar they almost blend into the scenery of rice paddies and pine hills.
The Koreas remain technically in a state of war since the 1950 to 1953 Korean War ended in an armistice, not a peace treaty. US forces say the South need not worry about being left vulnerable.
"We fought throughout the Korean War, and we'll be prepared to fight alongside our ROK [Republic of Korea] allies and defend this peninsula,'' said Lieutenant Colonel Patrick Stackpole, the 2nd Infantry Division's operations officer.
North Korea keeps two-thirds of its 1.1 million-strong military near the border and could bombard Seoul with thousands of artillery shells within minutes of an outbreak of war. South Korea also positions most of its 650,000-strong military near the border, and is backed by 37,000 US troops.
The US military has yet to reveal a timetable for withdrawing from the DMZ, but says that repositioning the troops to "hub bases" further south, out of North Korean artillery range, will give them more flexibility to deal with any North Korean attack.
The moves are part of a broader Pentagon strategy to realign US forces around the globe, likely to include reductions in Germany and new bases in eastern Europe. Last month, the US pulled its troops out of Saudi Arabia after 12 years.
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