The U.S. military began deploying the Terminal High Altitude Area Defense (THAAD) system to South Korea on Monday, the same day North Korea launched four missiles that landed off the Japanese coast.
The United States and South Korea say the system is a necessary defense against Kim Jong Un's regime, but Beijing rejects the plan.
"I want to emphasize that we firmly oppose the deployment of THAAD," said Geng Shuang, a spokesman for China's Foreign Ministry, at a daily press briefing in Beijing on Tuesday. "We will resolutely take necessary measures to defend our security interests."
"All consequences entailed from this will be borne by the U.S. and the Republic of Korea," he said.
Geng did not provide details on what "consequences" are in store, but South Korea is bracing for retaliatory measures against its business interests, according to a South Korean official.
The Chinese side sees THAAD as a threat to the Chinese military and evidence of U.S. meddling in East Asian affairs. To signal its anger, Beijing has been taking aim at South Korean businesses in China and, since March 3, warning would-be Chinese tourists about booking trips.
Although some travel agencies have already stopped selling tickets and tours to South Korea, China's National Tourism Administration has officially ordered travel agencies to stop all tour groups and cruise ships by March 15, the South Korean official said.
The new measures would also shut down duty-free shops run by Lotte, the South Korean conglomerate that helped Seoul secure land for THAAD, according to the South Korean official.
A representative of China's Tourism Administration said by phone that the agency has indeed advised travel agencies not to sell South Korea tours or tickets.
The South Korean official and the Chinese tourism representative spoke on the condition of anonymity because they were not authorized to give information to the news media.
Three large Chinese travel agencies confirmed the order from the Tourism Administration. Two said they have already stopped selling packages; the other said it would stop selling by March 15.
The effort to throttle South Korea's thriving tourist trade is part of an ongoing campaign.
After Lotte helped the South Koreans secure land for THAAD, its business was denounced and threatened in China's Communist Party-controlled press. Nearly two dozen of the company's retail outlets were subsequently shut down by Chinese authorities for alleged safety violations.
In the run-up to the THAAD deployment, China rejected applications by Korean airlines to add charter flights on popular tourists routes, a move interpreted in South Korea as a warning on the missile system.
There have also been scattered efforts to implement at a pop-culture blockade, with South Korean television programs pulled from Chinese websites, calls for boycotts of South Korean cosmetics and canceled K-Pop (Korean pop) shows.
Politically motivated attacks on foreign business are strikingly at odds with China's recent calls to protect globalization and free trade, most notably President Xi Jinping's keynote speech at the World Economic Forum in Davos, Switzerland.
On Monday, South Korea said it was considering filing a World Trade Organization case against China, according to the local press.
Joo Hyung-hwan, South Korea's trade minister, said Seoul would "seek international action against possible violations of the World Trade Organization and the Seoul-Beijing free trade agreement."
He also pledged to help South Korean companies deal with any "discrimination" they face.
The South Korean official called China's moves "regrettable," noting that curbing business will hurt Chinese vendors, too.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)