Next to a river flowing from lush green hills, Lim Sun-bun, 64, tills her land — onions, garlic, potatoes and peppers.
She's lived in rural Seongju county, about 130 miles from Seoul in the southeastern region of the Korean Peninsula, all her life. It's a quiet, conservative, agricultural place, famous for growing melons.
But this past winter, Lim started hearing U.S. helicopters overhead.
"They fly low, and it's scary," she says. "No one asked us if we want to host this U.S. base. I'm worried about contamination of this river — our livelihood."
In the hills behind Lim's village, helicopters are airlifting equipment to a repurposed golf course where the U.S. military has been installing THAAD — the acronym for Terminal High Altitude Area Defense, a new U.S. missile defense system. Declared operational this week, it's designed to shoot down North Korean missiles.
But locals say: Not in my backyard.
In recent months, a protest camp formed in Lim's village. On a recent morning when NPR visited, local children were performing what was billed as an anti-THAAD dance in the village square — to a song about resisting imperialist forces.
"Go away, THAAD," they sang. "Come, peace."
Thousands have traveled to Seongju from all over South Korea to voice their opposition to THAAD. Many are in favor of dialogue with North Korea, and believe the presence of U.S. troops and weapons could put South Koreans in danger.
Buddhist monks have set up a shrine and hold vigil right next to an access road to the golf course, alongside a squadron of policemen on guard. Citizens are not permitted to get closer.
"It's not only a regional issue," says Choi Sung-hee, a former art teacher who traveled to Seongju to camp out and protest. "It's about peace, and how we Koreans can stop war and future weapons together."
South Korea's former president, Park Geun-hye, who was ousted in March, agreed in 2012 to host THAAD after a nuclear test by North Korea. But now Park is on trial for corruption, and there's an election next week to replace her.
In TV debates, the liberal front-runner, Moon Jae-in, has said he wants to rethink THAAD and objects to how the U.S. appears to have rushed its installation before the election.
China objects to more U.S. weaponry in the Asia-Pacific region, and has called for a boycott of South Korea and its products. That's a worry for businesses catering to the lucrative Chinese market.
In a touristy shopping district of Seoul, cosmetics vendors yell out what's on sale — in Mandarin. Chinese tourists are their biggest clients.
"But THAAD is hurting our sales, here and in China," says store manager Cho Ah-jin. "There's a boycott of Korean cosmetics, and Chinese tourists have stopped coming."
Tourist arrivals from China dropped by nearly half this past March compared to the previous year.
Banks in Seoul have started to offer special loans to businesses hurt by the Chinese boycott. A recent report by a Korean think tank estimates the Chinese boycott will cost South Korea some $7.5 billion this year — amounting to half a point of GDP.
In rural Seongju, THAAD is already operational. But as Chinese pressure on South Korea continues, whoever is elected president next week may find THAAD at the top of his or her agenda.
Jihye Lee contributed to this story.