Seoul is coming under increasing pressure to sharpen its strategic calculations as its relations with China appear to have plunged to their lowest ebb in years, amid friction over plans to station an advanced U.S. missile defense asset on the peninsula.

The downturn came as the security dynamics surrounding Northeast Asia took a new turn, given that Pyongyang tested what it claimed was a hydrogen bomb last month and launched a rocket early this month.

The provocations prompted South Korea and the U.S. to launch formal talks to deploy a Terminal High Altitude Area Defense battery here. In response, Beijing has lodged a series of protests as it regards the equipment as part of a U.S.-led global missile defense program targeting China.

On Tuesday, tension hit a new high after Chinese Ambassador to South Korea Qiu Guohong warned during a meeting with the interim leader of the main opposition party that the two nations’ ties could be “destroyed in a flash” due to one single problem, referring to THAAD.

The remarks reverberated across diplomatic circles here, as the Park Geun-hye administration has until recently flaunted achieving the “best” relationship with China as one of its foreign policy feats. Cheong Wa Dae made an unusually stringent argument for THAAD the following day, while Seoul’s Foreign Ministry summoned Qiu to deliver complaints.

“For South Korea, THAAD seems inextricable from the North Korean nuclear issue and thus the country is approaching it from a sovereign standpoint -- for the sake of the safety of the people and national security,” said Kim Han-kwon, a professor at the Korea National Diplomatic Academy.

“But in fact it serves more as an element of the strategic rivalry between the U.S. and China that has been unfolding in the South China Sea, the East China Sea and is now about to spill over into the West Sea, placing Beijing under a great deal of pressure.

“As the circumstances stand, the envoy’s words was probably deliberate and meant to sound out the views of various parts of society including the opposition camp and the press,” Kim added.

Aside from its “undiplomatic” nature, for which Qiu took much flak, his comment partly reflects Beijing’s discontent with the growing accusations from Seoul and Washington for not putting enough pressure on Pyongyang to stop making nuclear weapons, some analysts say.

During the visit, Qiu sought to blame the allies for hampering the ongoing U.N. Security Council discussions on imposing new sanctions on North Korea by announcing the THAAD plan.

Douglas Paal, vice president for studies and director of the Asia program at the Carnegie Endowment for International Peace in Washington, said there appears to be an “unusually highly emotional character” to China’s responses to calls by the U.S. and South Korea for tougher action against Pyongyang, ascribing it to the “high expectations China had last fall that they had North Korea moving in the right direction.” 

Late last year, concerns soared that North Korea may fire another long-range missile chiefly to coincide with the military parade marking the 70th anniversary of the founding of the ruling Workers’ Party in October. But no major provocation took place as Beijing dispatched for the event Liu Yunshan, a member of the Standing Committee of the Chinese Communist Party.

“The U.S. administration also reacted without much thought about the effects of its statements, such as Secretary of State John Kerry’s initial curt dismissal of China’s approach to getting the North to denuclearize. This would have made me angry if I were a Chinese official,” Paal noted.

“Seoul should have reserved a decision on THAAD until after the UNSC resolution was passed. Now Beijing is using THAAD to try to change the subject of conversation from the North’s provocations to Washington and Seoul’s strategic calculations against Chinese missile capabilities.”

The relations between South Korea and China face a rough ride given the slim chances of a reversal of the THAAD plan.

But Seoul can “adjust the speed” of its consultations with Washington on the stationing, according to Beijing’s sincerity in implementing the upcoming UNSC resolution, while assuring that the system is designed to counter North Korean threats, not to keep China in check, Kim said.

Kerry, for his part, made the point at a joint news conference with Chinese Foreign Minister Wang Yi on Wednesday in Washington that if North Korea were denuclearized, THAAD would not need to be deployed on the peninsula.

But others pointed to the stark reality of the regional security landscape where some level of discord is inevitable, as all states jostle for their own interests, however cordial their two-way ties may be.

“In order to have a relationship with China of mutual respect and on equal footing, Seoul needs to stand up to China,” Bonnie Glaser, a China specialist at the Washington-based Center for Strategic and International Studies, said in an email interview with The Korea Herald.

“Friction may be unavoidable in the relationship. Beijing is angry because the ROK is standing up for its own interests, South Korea has every right to do whatever is necessary to defend itself against hostility from the North.

“Instead, assurances should be provided to China that THAAD will not be deployed in a mode that will enable it to have coverage over a significant portion of Chinese territory.”

By Shin Hyon-hee (heeshin@heraldcorp.com)