A visitor passes under LED light decorations ahead of the 2018 PyeongChang Winter Olympic Games in Gangwon Province, South Korea, on Thursday. (Bloomberg News)

The opening of the Olympic Winter Games in South Korea comes at a time of increased regional tensions. North Korean nuclear and missile tests throughout 2017 — showcasing new capabilities — and harsh rhetoric from Pyongyang and Washington have put the region on edge.

The Games could play a calming role. North Korea will send athletes south, and the two Koreas will “march together in the opening ceremony and field a joint team in women’s ice hockey.” The official North Korean delegation includes Kim Jong Un’s sister and close adviser, Kim Yo Jong — a signal that the North may be taking this opportunity for meetings seriously. And Vice President Pence did not rule out meeting with the North Koreans while in attendance.

But there are other tensions — and a long history — that affect regional economics and security, as well as U.S. alliances. Here’s the backstory on three challenges, and how they play out in 2018:

1) Seoul and Tokyo squabble over the past. At a November state banquet in Seoul, President Trump was served large shrimp and hugged an 88-year-old woman named Lee Yong-soo, sparking a spat between America’s two closest allies in East Asia.

The shrimp in question came from “Dokdo — a rocky outcrop known in Japan as Takeshima.” South Korea administers the islands, but both Tokyo and Seoul claim sovereignty. This is just one of many rival claims to islands in the region, from the longstanding disputes in the South China Sea and competing claims between China and Japan over islands in the East China Sea. Seoul’s inclusion of the shrimp prompted the Japanese government spokesman to wonder “if it had been wise to make such diplomatically sensitive gestures.”

Far more contentious, though, was Lee Yong-soo’s attendance. Lee is one of the few remaining “comfort women,” out of the estimated 200,000 women the Japanese military forced into sex slavery during the 1930s and 1940s.

To Koreans, the Japanese government was slow to apologize. An agreement in 2015 was supposed to end the issue, with Japan apologizing and expressing its remorse, while also providing $9 million to “support surviving victims.”

For its part, Seoul agreed to “make efforts” to remove a statue in front of Japan’s embassy in Seoul depicting comfort women. South Korean President Moon Jae-in, though, recently called upon Japan to apologize once again. Despite some concern that the issue might keep him from attending, Japanese Prime Minister Shinzo Abe will be at the Opening Ceremonies and reportedly will “clearly state Japan’s stance” on the 2015 deal.

Abe’s decision to attend the Games has led to conservative backlash in Japan. Some Japanese legislators believe Abe should stay home — while others on the right made historically inaccurate claims regarding the comfort women. This backlash, along with what political scientist Jennifer Lind terms Tokyo’s “unapologetic remembrance,” continue to infuse the relationship with mistrust, and “elevates threat perception and inhibits reconciliation.” Likewise, she found that efforts by Japanese leaders “to apologize galvanized Japanese conservatives to deny, justify, or glorify Japan’s past behavior.” This vicious cycle doesn’t seem likely to end soon, especially when the current prime minister has visited the controversial Yasukuni shrine for Japan’s war dead — including some war criminals.

2) The Vietnam War casts a long shadow over Southeast Asia. With the Olympics taking place so close to the DMZ, the possibility of a future conflict will no doubt hang over these Games — but there is another older conflict that continues to shape U.S. relations in the region: the Vietnam War. Vietnam and the United States recently have been moving closer together in order to check China’s moves in the South China Sea. Both China and Vietnam stake claim to the Spratly Islands, and Hanoi has loudly opposed China’s claims. This drives Vietnamese attempts to boost military relations with the United States and its regional allies.

Defense Secretary Jim Mattis conducted a two-day visit to Vietnam in late January, solidifying growing ties. The United States announced during the trip that a U.S. aircraft carrier would go to Da Nang in March, the first visit of a ship this size since the Vietnam War. Moreover, the United States has begun to supply Vietnam with hardware, including a 2015 sale of Coast Guard ships.

Moving the bilateral relationship forward won’t be simple, given the long history of the Vietnam War. As Mattis found, reminders of the conflict are all around. For Americans, there are memories of protests and POWs, and the stigma of a losing war. For the Vietnamese, the “American War” killed hundreds of thousands of soldiers and civilians alike, with many in Vietnam still dealing with the health effects of U.S. chemical defoliants.

3) In history, China looms large. At least according to China, which will host the 2022 Winter Games. China has long used history to mold current issues to its benefit. Domestically, China uses history to ensure the continuation of the Chinese Communist Party Historian Paul Cohen has shown how Chinese, both within the 1920s New Culture movement and, more recently, the Communist Party, shifted myths regarding the 1900 Boxer Rebellion to fit their respective political needs. President Xi Jinping has maintained and in some ways intensified the use of selective history for his domestic political purposes.

Externally, China takes a similar approach. Beijing’s massive Belt and Road initiative (which now includes the Arctic) “is designed to revive the ancient Silk Road and the maritime spice routes” from centuries ago. Xi pushes a “narrative of rejuvenation,” with the Belt and Road as the key to reclaiming China’s regional dominance.

And there’s a very real near-term conflict sparked by China’s use of historical claims to the South China Sea. Beijing continues to undertake massive reclamation and construction projects on disputed islands and outcroppings in the South China Sea, as it seeks to dominate the strategic waterway. This has been highly contentious, as a number of other nations also claim portions of the region. The United States, for its part, has pushed back against Chinese construction and sent multiple naval flotillas through the area in freedom of navigation exercises.

All of these forces from the past place distinct stresses on U.S. regional alliances at a pivotal time for the region’s history, and add a subtext beyond the cheerful athletes and fluttering flags of the Olympic ceremonies. Resolving these specific issues will require some deft diplomacy — and perhaps help in the bigger diplomatic goal of easing tensions in Asia.

Kelly M. McFarland (@McFarlandKellyM) is a U.S. diplomatic historian and director of programs and research at Georgetown University’s Institute for the Study of Diplomacy, and an adjunct professor in the School of Foreign Service at Georgetown.