Security experts from South Korea and China held a heated debate last week on the possible deployment of an advanced U.S. missile defense system on South Korean soil.

At a forum in Shanghai, a Chinese participant voiced his objection to the move that he said would pose a threat to China’s security interests.

A South Korean scholar refuted the Chinese stance, saying Seoul “cannot help but deploy” the Terminal High-Altitude Area Defense battery to deter growing threat from North Korea’s ballistic missiles. He noted the South is now incapable of intercepting a missile flying from the North at an altitude higher than 100 km.

Nam Sung-wook, a professor at a Seoul university, also called on China to “play a more active role” in persuading the North to abandon its nuclear weapons program.

His sensible remarks ought to be echoed by more politicians and administration officials here, who have kept largely mum about sensitive issues between Seoul and Beijing.

In a meeting with a dozen South Korean lawmakers earlier last week, Chinese Ambassador to Seoul Qiu Guohong made public his opposition to the possible deployment of the advanced missile defense system here. He was quoted by a lawmaker as warning that, if South Korea allows the U.S. to deploy a THAAD battery on its soil, it would hurt its relations with China.

It may be understandable that Beijing is concerned particularly about the far-reaching radar system of the THAAD, which could monitor military facilities and movements in China. The ambassador’s remarks, though, were inappropriate and gave the impression of interfering in Seoul’s sovereign decision on its defense posture.

Taking China’s concern into account, South Korea has remained cautious on joining the U.S.-led regional missile defense shield. Instead, it has been developing its own Korea Air and Missile Defense system. But Seoul officials have recently said they will not oppose Washington’s possible plan to bring a THAAD battery here to protect its troops. This move would eventually help defend the South against threats from the North, which is believed to be close to placing nuclear warheads on its ballistic missiles.

South Korea has the sovereign right to adopt the best possible defense scheme to strengthen its security posture. For many people here, it seemed improper ― and even impudent ― that the Chinese envoy gave a warning message regarding this matter in his meeting with South Korean lawmakers.

It was equally disappointing that none of the lawmakers came forward to refute his remarks and call on him to respect South Korea’s sovereign choice. They should also have expressed regret over the Chinese diplomat’s objection to a recent U.N. resolution condemning North Korea’s dire human rights conditions.

Administration officials too made no response to Qiu’s remarks. This cautiousness is in sharp contrast to their quick denial in the past of Washington’s suggestion that it had held discussions with Seoul on THAAD deployment.

South Korean politicians and officials have refrained from speaking up about other thorny issues with China, including illegal operations by Chinese fishermen in the waters off the country’s west coast. Liberal civic organizations here, which have been critical of deals with the U.S. and Japan, have become reticent about negative aspects of ties between South Korea and China.

This passive tendency may result from a complex set of reasons: growing economic reliance on China, Beijing’s leverage over the recalcitrant regime in Pyongyang and the psyche formed through unequal relations in the pre-modern era.

South Korea needs to be more forthcoming in making its case with China. Certainly, South Koreans should not be overconfident of what they have achieved over the past decades. But their accomplishment has put the country in a position to get its voice heard by major powers. South Korea should step up to make China give it the attention it is due.