Ground-penetrating radar machines, which can search for objects up to 10 meters deep, are being used by the U.S. military on Camp Carroll military base in South Korea to check if supplies of Agent Orange was buried there.
Concern in the local community of Chilgok, 300 kms (186 miles) south of Seoul is clear.
Posters are draped over the railings surrounding the U.S. military base, all with the same message to the U.S. military: Start digging and start apologizing.
One lone protester at the gates of the base holds a placard that reads: ‚ÄúThis land is not the graveyard of Agent Orange.‚ÄĚ
Four U.S. veterans allege they were ordered to bury barrels of the toxic herbicide on the base in 1978 - allegations that have shocked South Korea.
"I'm very concerned," District Gov. Seho Jang told CNN. "It greatly affects the survival of the entire area and people.‚ÄĚ
The U.S. military insists it has no records of Agent Orange ever being stored or disposed of on this base, but it says records do show 65 drums of herbicides, pesticides, solvents and other chemicals were buried on Camp Carroll in 1978.
The military says those drums were dug up again a year later and prepared for shipment, but that's where the trail goes cold.
The U.S. military says their No. 1 priority is to find out where those drums ended up.
Lt. Gen. John D. Johnson is in charge of the investigation and escorted concerned South Korean officials around the base.
He told Jang: "I pledge to be completely open and transparent to make sure you and the Korean people have all the info you need to know what's happening."
Johnson says he sent one of his officers to the U.S. to question the veterans who made the allegations and from their testimony, two areas of the camp will be tested with ground-penetrating radar. Soil and underground water testing will follow.
The U.S. military sprayed Agent Orange from planes onto jungles in Vietnam during the war to kill vegetation in an effort to expose guerrilla fighters.
Exposure to the chemical has been blamed for a wide variety of ailments, including certain forms of cancer and nerve disorders according to the Department of Veterans Affairs, as well as being linked to birth defects.
According to the Korean Agent Orange Victims Association, 58,000 Korean veterans are direct Agent Orange victims.
The association's Secretary-general, Sung Wook Kim, saw first-hand the effects of Agent Orange in Vietnam.
"I get goose bumps just thinking about these allegations ... but we're not convinced they're true," he said. "Fighting alongside the U.S. military in Vietnam, dozens risked their lives to save one soldier. I doubt they would have buried toxic chemicals on their own base.‚ÄĚ
The U.S. military wants to turn those doubts into facts. The high-profile investigation is meant to calm fears and stop any anti-American sentiment before it can take hold.