China's opposition to South Korea's decision to host the US THAAD missile defense system shows Beijing believes neighboring countries must put China's national interests ahead of their own, a US expert said Wednesday.

Mark Tokola, vice president of the Korea Economic Institute of America in Washington, made the point in an article posted at KEI's blog website, stressing that it is North Korea's nuclear and missile development that led to the decision to place THAAD in the South.

"China continues to assert what it considers a self-evident right to a sphere of influence in Asia, within which neighboring countries must give priority to China's national interests," said Tokola, a former diplomat who served as deputy chief of mission at the US Embassy in Seoul.

"China would be a more reassuring regional partner if it acknowledged that the cause of tension on the Korean peninsula is North Korea's pursuit of offensive weapons, not South Korea's deployment of defensive systems," he said.

Tokola also said that China's opposition to THAAD also reveals that it has "difficulty crediting the idea that there can be developments within Northeast Asia that are not really about China, i.e. that South Korea might have a specific interest in defending itself against a belligerent North Korea."

China has strongly protested the decision, claiming that the system, especially its powerful "X-band" radar, can be used against it, despite repeated assurances from the US and the South that the system is purely defensive and designed only to cope with North Korean threats. (Yonhap)