One day the system could destroy North Korean missiles in mid-flight, a remarkable feat of military might and technical prowess.
But so far, its main victims have been South Korean pop stars, cosmetics companies, and TV shows.
Washington and Seoul plan to deploy the U.S.-developed Terminal High Altitude Area Defense (THAAD) anti-ballistic missile system on South Korean soil before the end of the year, a long-envisioned response to North Korea's repeated missile tests and threats to attack South Korea, Japan and the United States.
Yet Beijing, a longtime ally of Pyongyang, sees the system as part of a U.S. strategy to contain China, since it could also be deployed against Chinese missiles. And as THAAD's deployment date draws near, its denunciations have reached fever pitch, spurring retaliations online and in the streets.
Chinese authorities have denied visas to South Korean pop stars who frequently perform on the mainland; rejected imports of South Korean cosmetics; and scrubbed at least five enormously popular South Korean TV shows — some with hundreds of millions of Chinese viewers — from Chinese video streaming sites.
"We don't have to make the country bleed, but we'd better make it hurt," the Global Times, a Chinese state-run tabloid, said in an editorial on Wednesday.
The measures have stirred anxiety in South Korea's business community, upset Chinese TV fans and cast uncertainty over the future of the China-South Korea relationship, which has enjoyed relative stability since the 1990s, enabling huge amounts of transnational commerce and migration.
China is by far South Korea's largest trading partner.
Shi Yinhong, a professor of international relations at Renmin University in Beijing, said that China — angered by North Korea's recent missile tests — now faces strained relations with both Koreas for the first time in recent memory.
"This is quite bad, in the long term, for the diplomatic security environment in Northeast Asia," he said.
Beijing has issued two "solemn representations" to Seoul over the impending deployment, and the People's Daily, a Communist party mouthpiece, said in an editorial that Beijing could potentially sever diplomatic ties.
But the measures have also played out in more minute and unexpected ways.
On Tuesday, after months of negotiations, South Korean retail giant Lotte Group reached a deal to swap land at its Lotte Skyhill Country Club — a lush, mountainous resort in on the southern side of Jeju Island — for a military-owned parcel on the outskirts of Seoul, making way for the missile shield to be placed on the country club site.
That same day, Chinese authorities fined one of Lotte's Beijing supermarkets $6,500 for displaying a "false advertisement" — a vanishingly rare charge in the city, according to the state-run Legal Daily.
The fine, while negligible for Lotte — one of South Korea's largest conglomerates — adds to a long list of challenges in the country. Lotte suspended construction of a planned $2.6-billion theme park project in the northeastern Chinese city of Shenyang last month after facing several fire, safety and tax investigations. Authorities have also targeted Lotte businesses in Beijing, Shanghai and the southwestern city of Chengdu.
On Wednesday, Lotte's Chinese website was inaccessible, showing only the message: "Lotte's official webpage is undergoing maintenance. Please forgive any inconvenience." Its South Korean page remained accessible. The cause of the outage is unclear.
Starting last year, Chinese authorities have forbidden Korean stars from appearing on Chinese TV programs and soap operas; one Korean reality show participant, singer Hwang Chi Yeul, was abruptly replaced by an actor from Hong Kong. They have also banned imports from 19 Korean cosmetics brands.
Since Feb. 24, at least five Korean TV shows — including the extraordinarily popular variety show Running Man — have been inaccessible on Chinese video websites.
South Korea's economy is heavily dependent upon exports, about a quarter of which go to China, and experts say that the measures could take a bite.
"Economic sanctions by China may have a substantial impact on the Korean economy as a whole, and especially on certain business sectors" such as its entertainment industry, said Sangin Park, an economics professor at Seoul National University.
South Korean pop culture, exemplified by K-pop music and TV soap operas, is one of the country's most important exports, and not just economically.
Troy Stangarone, a senior director at the Korea Economic Institute of America, said China risks overplaying its hand by blocking popular South Korean content and could, over time, push its neighbor toward investing in other regional economies, such as Vietnam.
"Banning or prohibiting the update of additional Korean dramas is a risky course by the Chinese due to the popularity of the products," he said. "In the short term, it might have a negative impact on South Korea. There could also be a negative impact on China."
"It hurts China's image as a business-friendly country," he added.
Last week, the South Korean government said it was aware that some local companies have expressed concerns about China's new trade barriers.
"Despite a tightened Korea-China relationship, we keep in touch with China," said Woo Tae-hee, a deputy South Korean trade minister. He said South Korea would express its concerns to China under a communication framework that's part of a year-old bilateral trade deal.
South Korea plans to deploy the defensive missile system "before the end of the year," said Moon Sang-gyun, a spokesman for the South Korean defense ministry. He said that authorities are still working on environmental impact studies, facility construction and final negotiations with American officials.
Despite the tensions, the number of Chinese visitors to South Korea increased more than 8% from January 2016 to the same month this year.
Zhu Quanjingzi, 24, a human resource professional in Beijing, said her feelings about THAAD were "a little complicated."
"I oppose THAAD — I think it poses a threat to China's safety," she said. She plans to stop traveling to South Korea as a tourist, and boycott Korean cosmetics.
"But I cannot live without Korean TV shows," she said. "I can watch them on YouTube."
Times staff writer Kaiman reported from Beijing and special correspondent Stiles from Seoul. Yingzhi Yang in the Times' Beijing bureau contributed to this report.
For more news from Asia, follow @JRKaiman on Twitter