When a cruise ship recently docked at South Korea’s southern resort island of Jeju, it was astonished to find all 3,400 Chinese passengers on board refused to disembark, leaving about 80 tour buses as well as some tour guides all at sea.

According to local media reports, the cruise ship's captain as well as the South Korean personnel at the customs and quarantine department were unaware of the situation until the ship docked at the port on Saturday afternoon. It was reported that the Chinese passengers were staff from a Chinese enterprise on a trip organized for them as a reward.‍

It was the first time that such a large group of passengers refused to disembark at Jeju in over two decades. The Costa Serena cruise ship's home port was Japan’s Fukuoka, and it stayed at Jeju for about four hours before setting off for its next stop at east China’s Tianjin port.

South Korean media said two ships run by Costa Serena, an Italian company, have canceled a total of 26 sailings to Jeju island from mid-March to the end of June. That might mean an estimated 120,000 fewer Chinese tourists visiting Jeju island.

The resort island has been popular with tourists from China in recent years, but the unusual event on Saturday comes amid a standoff between China and South Korea over Seoul's determination to deploy the US THAAD missile defense system, despite Beijing’s repeated opposition. Media cited a survey by the Korea International Trade Association, saying that more than half of some 600 businesses in the tourism, retail and cultural sectors have been hurt since relations deteriorated.

Beijing said the attitude of the Chinese people towards the South Korean decision to deploy THAAD clearly shows strong opposition to the move, and warned South Korea should be aware of the Chinese people’s voice. The statement was made in response to a land deal reached by Lotte Group, South Korea's fifth-largest chaebol conglomerate, and the South Korean military at the end of February, which further smoothed the path to place THAAD on the Korean Peninsula.

THAAD has a very limited capability when it comes to countering missile threats from the north, as it is designed to intercept incoming missiles at an altitude of 40-160 kilometers. Pyongyang’s indigenous missiles can technically fly at an altitude far less than 40 km, which would not be in THAAD's range.

However, THAAD's X-band radar is capable of looking deep into the territories of China and Russia, causing strong backlashes from the two countries. Two ground-based X-band radars for THAAD were placed in Japan about ten years ago.