Left in a locked room alone, she could hear other people but not see them. Armed men were guarding the house.

Diep had just been looking for a way to make ends meet.

Growing up in a poor family with five siblings, her parents could not afford to pay for their education so she left school at 14 to work in a factory. After three years there, she moved on to jobs in clothing stores and restaurants in Ho Chi Minh City. But the wages were low and her financial situation barely improved.

In 2019, a man, who was a friend of a friend, reached out to her on Facebook, offering a job in Myanmar.

After multiple meetings with him to discuss the offer – a well-paid waitressing position – she eventually decided to accept the role and flew with him to Myanmar.

“The opportunity was so exciting. I would be able to save money and… help my parents and buy them new clothes,” Diep said.

After arriving at the airport, Diep was transported across the country for 24 hours in several different cars, until they reached Shan state.

Locked in her room, Diep was told her job was to be a sex worker. Furious, she refused.

Her captors, determined to subdue her, gave her a severe beating but despite the pain, she continued to resist, insisting she would not be forced into prostitution.

It was only after the men guarding the house visited her room and raped her that Diep gave in. She was told that if she did not agree to do sex work, her daily punishment would be rape.

While Diep was now allowed to interact with other women – some of whom were also Vietnamese – elsewhere in the house, they were all forced to take crystal meth. Their captors claimed the drug increased women’s endurance and libido.

She wanted to escape but soon realised how dangerous that might be – and that it could get her killed.

“I cannot believe I was in that situation,” Diep said. “Even in my worst nightmares, I never thought my life would become like that.”

One day, however, with the help of the Blue Dragon Children’s Foundation, a Hanoi-based NGO that rescues victims of human trafficking, another woman Diep had befriended managed to get away.

In the end, it was also Blue Dragon that devised a plan to rescue Diep, who had been allowed to use a phone.

By the time she arrived back in Vietnam, Diep was 22 and had been held in sexual slavery for more than three years.

“Realising that I was free, that I was home, that I would be able to see my parents again, that the pain had ended…That was such a shock. I couldn’t believe it,” Diep said.

“Sometimes, I hope my time there was just a bad dream,” she added. “But then, sometimes, when I’m home, I think this is a dream… and I get scared that it isn’t true, that I’m just dreaming, and I’m still trapped there.”

Blue Dragon says it cannot share precise details about such rescues because doing so would risk endangering future attempts to bring these women back to Vietnam. Diep’s story, however, is not unique. Blue Dragon has recently reported a sharp rise in the number of Vietnamese women being trafficked into Myanmar.

Human trafficking patterns are shifting in part due to a huge fence China has constructed along the country’s southern border with Vietnam, Laos and Myanmar. The three-metre-high (10 feet) fence, which is electrified, topped with razor wire, equipped with motion sensors and runs for at least 1,000 kilometres (621 miles), has had a significant effect on informal migration.

“The border fence makes crossing between countries much more difficult for traffickers,” Michael Brosowski, the founder of Blue Dragon, told Al Jazeera. “Previously, they would take their victims across mountain trails and rivers into China undetected. Now that they can’t do so, the traffickers have opened up new destinations to take their victims to. We’ve seen a growth in trafficking to northern Myanmar, Cambodia and, to some extent, Laos.

While the trafficking of Vietnamese women to China for forced marriages or sexual exploitation has continued at a much lower level, there has been a clear increase in the number of individuals trafficked into labour exploitation in Cambodia, which is grappling with a gang-led cybercrime crisis, and to Myanmar, where people– mostly women – find themselves forced into the sex trade.

The fence also means that Vietnamese living in remote, mountainous areas near the Chinese border, who once relied on informal migration and employment in China for their income, have been cut off from their usual job opportunities. Desperate for money, they have become increasingly susceptible to the traffickers’ talk of high-paying jobs overseas.

In 2020, Blue Dragon rescued 274 Vietnamese trafficking victims from China, while that figure dropped to 110 in 2022. From Cambodia and Myanmar, they rescued 62 and 44 individuals from each country respectively in 2022 – in 2018, the figure in those two countries was zero.

Despite the growth, there has been little coverage of Vietnamese being trafficked to Myanmar in Vietnam’s state media, with most reports focusing on Vietnamese being forced into slavery in Cambodia as well as warnings from Vietnam’s Ministry of Public Security against “easy money” job promises in Cambodia.

Like Diep, Hanh*, another sex-trafficking victim in Myanmar, said she was forced into prostitution, treated violently and made to take crystal meth. She faced a constant threat of violence and witnessed multiple shootings around her. She said Vietnamese citizens were among those guarding the brothel.

One day, a woman tried to escape. Hanh says her captors caught the woman, stripped her naked in front of the house, deprived her of food and “chained her like a dog, for everyone to see”.

Hanh, who faced financial difficulties during the COVID-19 pandemic, was trafficked to Myanmar in the latter half of 2021 and made it home to Vietnam with the help of Blue Dragon in September 2022.

Transnational criminal gangs

The brothels in Myanmar are probably run by the same criminal gangs known to operate online scam factories and casinos in Cambodia, which expanded rapidly during the coronavirus pandemic when many people were easy targets for online fraud and gambling.

“Reports from the hundreds of people we have spoken to indicate that the criminals running the brothels in Myanmar and the online scams in Cambodia are Chinese gangsters, operating out of reach of their government who would never allow them to commit these crimes at home,” Brosowski said.

In Cambodia, Laos and Myanmar, trafficking victims are mostly taken to special economic zones (SEZs) in border regions, where the rules are looser. In Myanmar, the conflict triggered by the February 2021 military coup has complicated the situation further.

Zachary Abuza, a Southeast Asia security expert at the National War College in Washington, DC, said he does not think there is a qualitative difference between the cyber-scam operations in Cambodia and the Chinese-backed SEZs in Kokang and Lashio, in Myanmar’s Shan state as well as Boten and Bokeo in Laos.

These areas are controlled by either Border Guard Forces linked to the military or other ethnic armed groups that have not joined the resistance against the coup.

“The coup in Myanmar has weakened the military’s control of parts of the country, especially the periphery, and boosted the prospects of transnational criminal organisations operating there,” said Richard Horsey, a senior adviser on Myanmar at Crisis Group.

According to the 2022 US Trafficking in Persons Report on Myanmar, efforts to combat trafficking “declined dramatically after the coup as the military regime shifted its focus away from other justice sector priorities and toward persecution of the pro-democracy opposition”.

“Civil society partners reported in 2021 an estimated 500 Vietnamese women in commercial sex in Wa State Special Administrative Region”, the report said, “an area with minimal regime control; some of these women reported indicators of sex trafficking”.

It warned the situation might get worse.

“Absent oversight and enforcement measures in non-government-controlled areas, often in border zones, women and girls from these border regions and elsewhere in Southeast Asia may be vulnerable to sex trafficking in casinos and Special Economic Zones owned or operated by EAOs and PRC and Thai companies,” the report added, referring to ethnic armed organisations and the People’s Republic of China.

Vietnamese people are being trafficked into Myanmar’s northern Shan state in particular, where local armed groups allow illegal brothels and casinos to operate, according to Blue Dragon.

According to Crisis Group, Shan State has “long been a centre of conflict and illicit drug production”, especially “in safe havens… held by militias and other paramilitary units allied with the Myanmar military”.

“For Vietnamese people to escape these northern states and return to Vietnam involves a long journey through jungles, over mountains, and across rivers –all with the risk of being shot or caught and sold again. What’s happening in this region is shocking, but hardly known to the world,” Brosowski said.

Dinh Thi Minh Chau, Blue Dragon’s chief psychologist, said: “All women we’ve rescued in Myanmar have had to go further than any other human being. They no longer care about the risk, they no longer care about dying, they just try to find a way to escape. They’re very, very focused on trying to find a way to get out.”

“The situation,” she said, “is just too terrible for anyone to endure”.

*Some names have been changed to protect identities.