President Obama’s recent visit to Vietnam was a historic reminder that the days of the Cold War are over. As the president took part in a town hall meeting with young Vietnamese in Ho Chi Minh City and sat down for noodles with Anthony Bourdain in Hanoi, the chaotic American evacuation from Saigon four decades before was nothing more than a distant memory. Of course, the realities of life in communist Vietnam couldn’t stay entirely hidden: several of the activists and civil society leaders Obama had planned to meet were prevented from seeing him.

Autocratic Vietnam still faces plenty of human rights issues, but the struggles of one socially ostracized group should strike particularly close to home for the president. Of the many lasting but little-discussed vestiges of the Vietnam War, one which receives little coverage is the plight of the Lai Dai Han community, which translates to “South Korean mixed-race” in Vietnamese. The Lai Dai Han are the children of Vietnamese women and South Korean soldiers who arrived during the Vietnam War to help their American allies against the North Vietnamese. At least some of the 300,000 South Korean troops who were sent to Vietnam have since been accused of systematically using rape as a weapon against Vietnamese civilian women.

In the same way the Korean “comfort women” pressed into sexual servitude have been a lightning rod in Korea-Japan relations, the use of sexual violence against the Vietnamese has been a sticking point in relations between Hanoi and Seoul since the end of the war. Within their own communities, many of the women who endured these rapes have been ostracized alongside their children. The estimated 5,000-30,000 Lai Dai Han face the same struggle as Vietnam’s Amerasian children, fathered by American servicemen and punished for their association with the enemy through no fault of their own. Mixed-race Vietnamese children tend to be poorer than their compatriots, forced to live with pariah status as a lasting reminder of the conflict and the foreign powers that fought in it.

Since last year, a new grassroots campaign has sought to raise awareness of the Lai Dai Han and their mothers. Called Voices of Vietnam, the group launched a petition at Change.org, calling on the South Korean government of President Park Geun-hye to issue a formal apology for atrocities committed during the war and to consider reparations. The text of the petition was written by Nguyen Thi Bach Tuyet, who saw her own mother raped by a South Korean soldier and was raped herself months later. Both women became pregnant, and after her mother died, she had to raise their children herself. Since last October, her plea has gathered over 34,000 signatures. For President Park to issue an apology would carry special significance for Ms. Nguyen and other victims of sexual assaults committed by Korean soldiers. It was Park Chung-hee, President Park’s father, who ruled South Korea as a military strongman and ordered troops into Vietnam starting in 1964.

While historians and policy experts can argue over the “real world’ impact of an apology, there is no doubt that the open, honest recognition of past wrongs is an incredibly important step in rebuilding trust between perpetrators and victims. With our own history of racial and ethnic injustice, the US is no stranger to apologizing for the mistakes we have made in the past. In 1988, the Civil Liberties Act signed by Ronald Reagan made amends for American internment camps during World War II by issuing a formal apology compensating over 100,000 Japanese-Americans. In the late 2000s, both the House of Representatives and the Senate also passed (symbolic) resolutions apologizing for the institution of slavery that defined much of early America’s history. Today, many argue convincingly for more formal recognition and serious debate over how to address the systematic poverty and inequality that slavery and segregation left us with. All this a decade after President Obama’s election seemed to herald a new, post-racial America.

The Lai Dai Han live in Vietnam, but their story has echoes in the US as well. As California deliberates its revised curriculum for history and social studies textbooks, Japanese-American and Korean-American communities have debated over how to handle the comfort women issue in their children’s education. The Vietnamese community is just as prominent in the state, however: 40% of America’s 1.3 million Vietnamese immigrants live in California, and Vietnamese-Americans are the sixth largest immigrant group in the US. As Asian-American groups have submitted comments and suggestions to the California state Instructional Quality Commission, several have spoken up for including the actions of South Korean soldiers in Vietnam as well. With so many distinct groups present in the state, tackling East Asia’s recent history of sexual violence in wartime is an important but delicate task.

Park Geun-hye has previously been reticent to pursue South Korean admissions of responsibility for events in Vietnam, but the growing ties between the two countries would only be helped by her tackling the issue head-on. The long battle over the treatment of Korea’s comfort women, settled by President Park and Japanese prime minister Shinzo Abe last December, was a critical step in healing the troubled ties between the two countries. As President Obama's time in Vietnam shows, former adversaries can transform their relationships — but only by being candid with each other about their shared past.