China-U.S. aerial tensions over Yellow Sea place Seoul in tight spot

SEOUL, South Korea — A series of recent high-stakes aerial incidents involving Chinese, Japanese and U.S. — but not South Korean — warplanes has become a flashpoint in the increasingly complicated alliance between Seoul and Washington.

The incidents may also signal that the U.S. is opening a new “front” in the region’s tense strategic geography, marked by naval and aerial challenges and counter-challenges.  

Beijing habitually makes clear its displeasure when other nations’ warships transit the Taiwan Strait. It also bristles at “freedom of navigation” naval patrols near the bases it has built in the South China Sea, and at “freedom of overflight” patrols in that area.

U.S. sorties last week from Korean bases into the skies over the Yellow Sea — a body of water China jealously guards — appear to be part of a new American-led test of the People’s Liberation Army and its air force.

Aerial chicken games in recent years have largely taken place over the East China Sea, the South China Sea, the Sea of Japan and the Taiwan Strait. For the People’s Liberation Army Air Force, the Yellow Sea lies uncomfortably close to home.

The situation presents a diplomatic conundrum for Seoul, which shares Yellow Sea coastlines with China and North Korea.

As tensions with China have ratcheted up, ties between Japan and the U.S. have tightened.

But South Korea is walking a fraying diplomatic tightrope between Washington and Beijing as it seeks to maintain optimal relations with the Trump administration while soothing its giant neighbor and trade partner China.

The Seoul-Washington divide

Since November, when Japanese Prime Minister Sanae Takaichi said Japanese forces would activate in the event of a Taiwan contingency, Beijing-Tokyo relations have plunged.

Beijing, which claims the democratic island, retaliated with diplomatic insults and restrictions of exports to, and imports from, Japan. That may have backfired. 

The landslide general election victory won by Ms. Takaichi in February greatly strengthened her hand to resist China, upgrade Japanese forces and tighten security links with Washington. Those links were on display last week.

Eleven Japanese jet fighters and four U.S. B-52 strategic bombers conducted bilateral aerial drills over the East China Sea and Sea of Japan — proximate to the southern entrance to the Yellow Sea on Feb. 16 and again, two days later, on Wednesday.

Domestic Korean media reported that Seoul was invited to join, but did not. Korea’s biggest national holiday, the Lunar New Year, spanned Feb. 16-Feb 18. Korea’s top newspaper reported Sunday that Seoul had asked for a schedule adjustment, but was denied.

Separately, on Wednesday, an undisclosed number of U.S. F-16 fighters launched from South Korea approached China’s Air Defense Identification Zone, or ADIZ, over the Yellow Sea.

An ADIZ lacks basis in international law, but is a widely followed protocol — and also widely ignored. China’s ADIZ overlaps with South Korea’s.

Though the U.S. jets were reportedly in international air space,  PLAAF fighters scrambled. No clashes were reported.

The U.S. fighters sortied from Osan Air Base, on Korea’s Yellow Sea coast, south of Seoul.

The Yonhap News Agency reported Saturday that the U.S. flights compelled South Korean Defense Minister Ahn Gyu-back and Chairman of the Joint Chiefs General Jin Young-sun to call U.S. Gen. Xavier Brunson, commander in chief of U.S. Forces Korea, to protest that Seoul had not been fully apprised of the scope of the mission.

Poking China

The Yellow Sea is hugely strategic for China.

The closest sea to capital Beijing, its seaboard is hosts aircraft carrier shipyards in Dalian in the northeast; China’s only nuclear submarine yard in Huludao in the north; and the Northern Fleet Command in Qingdao in the west.

In 2018, the U.S. completed a pivot of the bulk of its forces in Korea from Seoul and the inter-Korean DMZ to a series of bases lining Korea’s western Yellow Sea coastline.

Those bases are ideal for deterring China, and are the only U.S. bootprints inside the First Island Chain, the critical line for the defense of Taiwan.

For Seoul, the bases are sensitive, given its need to manage relations with Beijing.

Related stresses are coming into focus as the Trump administration makes deterring China the primary strategic objective of the 28,000-strong U.S. Forces Korea. And as the American mission has shifted, Mr. Trump has placed a bigger share of the burden of deterring North Korea onto South Korea.

The use of USFK as a region-wide force is dubbed “strategic flexibility.”

In January, U.S. Under Secretary of War Elbridge Colby, speaking in Seoul, focused heavily on China, not North Korea. USFK Commander Brunson has written and spoken widely on the geographic import of Korea for regional force projection.

These matters present a ticklish challenge for South Korean President Lee Jae-myung, who took office last year. He has established good relations with Mr. Trump — praising him and presenting gifts during their one meeting — but has also held two amicable summits with Chinese President Xi Jinping.

A new U.S. front

Regional analysts were taken aback by the apparent new U.S. focus on the Yellow Sea.

“I don’t know exactly over the West Sea where this happened, but I have a feeling it happened in the south,” said Chun In-bum, a retired South Korean general, of the flights.

“West Sea” is Korean nomenclature for the Yellow Sea.  

“For the last 50 years we have not done [aerial drills there] out of respect for China, though we had every right to, as it is in international air space,” Mr. Chun continued.  “Perhaps the Americans and Japanese realized that the good will has not been returned, as the Chinese have dominance in the West Sea.”

China, for its part, also seemed to be caught off-guard. Chinese military expert Song Zhongping told the Global Times newspaper that USFK “has rarely held military activities in this area before.”

“The U.S. has long regarded South Korea’s ADIZ as its own territory … its military operations in the area are aimed at simulating interception of aircraft from other countries entering the zone,” he continued. “But if the U.S. military shifts from defense to offense … the nature will be completely different.”

The Trump administration has been pressuring allies economically with tariffs on their exports. It has also been demanding European capitals upgrade defense spending while its comments over Greenland caused a near-panic in NATO.

The approach irks some U.S. commentators.

“It’s like a gangster protection racket!” said Daniel Pinkston, an international relations expert based in Seoul.

Mr. Chun suggested which capital Seoul should pivot toward.

“I am disappointed that Korea is still clinging to the idea of being as neutral as it can be,” between China and America, he said.

The recent developments show “that the window is closing, and we are going to have to make a choice, which is uncomfortable, but is the way things are on the Korean peninsula,” the former general added.

While Mr. Lee ponders options, two precedents exist. In both cases, Seoul sided with Washington against China — and suffered economic fallout.  

In 2017, USFK established a terminal high altitude defense battery — the American anti-missle system more commonly known as THAAD — in South Korea, infuriating Beijing, which claimed its radars could monitor China’s atmosphere.

Beijing retaliated, sanctioning  Korean companies, slashing tourism and halting imports of K-pop and K-dramas

Also in the first Trump administration, South Korea, the world’s leading maker of advanced memory chips, was forbidden by Washington, which owns key patents in the machinery used for fabrication, from deploying advanced machines to its fabs in China.

That restricted firms’ ability to manufacture advanced chipsets.

“The discomfort is great for Korea: It is not just for the politicians, but also for the business elite, for the firms,” added Mr. Pinkston. “U.S. allies have to figure out what the limits are.”