Thinzar Shunlei Yi was at home in Yangon, Myanmar’s largest city, on Monday morning when she realized she could no longer contact her friends. While her wired internet connection was working, her cellular network was dead.

“I had received a lot of calls in the early morning, but when I woke up, I tried to call them back and I couldn’t,” said Yi, an advocacy coordinator at the Action Committee for Democracy Development, a coalition of community-based rights groups. “I checked and there was no service at all, it had been cut off.”

Yi soon understood that Myanmar’s powerful military had taken control of the country overnight. “I was worried about friends, colleagues, leaders, politicians and activists,” she said. “Anything can happen at that time.”

On February 1, three months after Myanmar’s ruling National League for Democracy (NLD) won the country’s general election, the army seized power in a bloodless coup and declared a year-long state of emergency. Myanmar’s leader Aung San Suu Kyi and prominent members of the NLD were placed under house arrest. Power now rests with military chief Min Aung Hlaing.

The military alleges that widespread fraud took place in the November election, at the cost of the army-aligned Union Solidarity and Development Party, and has taken control of major cities and introduced a curfew.

A crackdown on the internet and mobile networks was central to the coup. Internet access fell by 50% on Monday, according to NetBlocks, a UK-based organization that monitors digital rights around the world. In a tweet, it said that the “pattern of disruption indicates a centrally issued telecoms blackout order.”

NetBlocks also revealed that users were unable to access at least two cellular networks. Myanmar is home to four main providers, the Myanmar-backed MPT, a Qatari company named Ooredoo and Norway’s Telenor. All three are rivals of the military-backed telecommunications company MyTel.

Rights groups have previously raised concerns about the potential security threats posed to MyTel users. In 2018, the European Union considered applying sanctions against it, in response to human rights abuses by the military that left thousands of Rohingya Muslims dead and drove more than 700,000 to flee to neighboring Bangladesh.

On the day of the coup, the activist group Justice for Myanmar posted on Twitter warning of potential surveillance by MyTel: “On Mytel + the other mobile networks, the military can monitor voice calls, SMS, location and some online activity. We appeal to activists, human rights defenders and journalists to take extra care of their safety in this dangerous and uncertain time by taking these steps.”

The group called for human rights workers and journalists to adopt a number of measures to protect themselves from surveillance, including boycotting MyTel, using end-to-end encrypted apps like Signal, and avoiding voice calls and the sending of SMS messages on all networks. 

While it is uncommon for a nation’s armed forces to invest in mobile and internet infrastructure, as is the case in Myanmar, military control of digital spaces can yield huge power over citizens.

“The communication disruptions are an attempt by the Myanmar military to pull a blind over its heinous actions, including arbitrary detention of prominent critics of the military, wrote a spokesperson for Justice for Myanmar in an email. “This has instilled fear among the public and disrupted the daily lives of many who rely on the networks to conduct their work, which for some has been crucial during the time of pandemic.”

The internet has provided authoritarian leaders and democratic governments with a valuable off-switch to control populations during times of crisis. Online blackouts, disruptions to connectivity and social media outages have been a hallmark of elections and protests in 35 countries since 2019, including Iran, Uganda and Ethiopia. Coda Story has previously reported on blackouts in India and the introduction of new laws limiting digital freedoms in Russia.

While cellular network and internet access has mostly returned to Myanmar, digital rights activists are concerned about future consequences for free speech as the military consolidates its control of the country’s institutions. On Wednesday morning, users on two Facebook groups, Myanmar Civil Disobedience Movement Funds and Yangon Youth Network, were calling for doctors, teachers and other professions to halt work in protest against the coup. 

“From a freedom perspective, I believe there will be more control of internet traffic,” said an employee of Internet in Myanmar, a technology news website, who spoke on condition of anonymity. “Since the last few months, the government started to introduce some filtering, I think we should expect that will happen more and more.”