ALMATY/LONDON/SEOUL (NYTIMES) - As Almaty, Kazakhstan's largest city, spiralled into chaos last month over rising energy costs and anger at the government, the country's leaders took a drastic step to quell protests: They blocked the Internet.

First, they tried to ban access to some news sites, social networks and messaging services. Then, as activists bypassed those curbs with software that masked their locations, the authorities shut down almost all connectivity in the country.

The moves added uncertainty to an already dire situation. After payment apps and point-of-sale machines used to swipe debit cards went down, lengthy lines formed at ATMs as Kazakhs rushed to get cash. Families could not communicate with loved ones. Taxi drivers who relied on ride-booking apps said they stopped driving because they could not connect with passengers.

"It was impossible to communicate," said Darkhan Sharipov, 32, an accountant who was part of the protests. "The lack of information multiplied the chaos and disinformation."

The scenes in Kazakhstan offer a preview of what may unfold in Ukraine, where the Internet could be one of the first targets of the Russian military in a potential conflict. Ukrainian and Western officials have warned that cyberassaults could be part of any Russian intrusion.

This week, the Ukrainian government said that the websites of two banks, its Ministry of Defence and its armed forces were briefly taken offline by a series of denial-of-service attacks, in which huge amounts of traffic overwhelm a network. The attacks were the largest in the country's history, Ukrainian officials said, and "bore traces of foreign intelligence services".

On Thursday (Feb 17), Internet service outages were recorded on some mobile networks in eastern Ukraine near the Russian border.

"In the event of a real military conflict, it is the Internet infrastructure that will be destroyed in the first place," said Mikhail Klimarev, a Russia telecommunications expert and executive director of the Internet Protection Society, a civil society group opposed to Internet censorship.

"In Kazakhstan, the Internet was turned off by order of the authorities," he said. "In Ukraine, we fear that the Internet will be disabled by shelling."

Control of the Internet is increasingly part of any modern conflict. Recognising that the web is vital for communications, economics and propaganda, authorities have increasingly used shutdowns to stifle dissent and maintain power, in what is akin to holding energy sources, water or supply lines hostage.

In 2020, there were at least 155 Internet shutdowns across 29 countries, according to the latest annual report from Access Now, an international non-profit group that monitors these events. From January to May 2021, at least 50 shutdowns were documented in 21 countries.

That includes in Yemen, where Saudi-led forces targeted the country's telecom and Internet infrastructure in the ongoing war there, according to Access Now. In November, Sudan's leaders turned off the Internet for nearly a month in response to protests. And in Burkina Faso, the government ordered telecom companies to turn off mobile Internet networks for more than a week in November, citing national security concerns.

"The only way to be absolutely sure that nobody is getting online is to pull the plug on everything," said Doug Madory, director of Internet analysis for Kentik, a telecom services company.

In Ukraine, any Internet shutdown would have to be done by an outside force, which is different than in Kazakhstan, where the government used national security laws to force companies to cut off connections.

Taking down the Ukrainian Internet completely would be cumbersome. The country has more than 2,000 Internet service providers, all of which would need to be blocked for a full shutdown.

Still, many expect targeted blackouts, particularly in Russia's and Ukraine's border areas, if there is war. Cyberattacks or a military attack could kill connectivity.

On Thursday evening, as fighting flared in eastern Ukraine near the frontline with Russia-backed separatists, cellphone service went down in what authorities said was "targeted sabotage". It was restored by Friday morning.

"Sabotage of communications facilities will continue," said Anton Herashchenko, an adviser to the Ukrainian minister of internal affairs. "All this is part of Russia's plan to destabilise the situation in Ukraine."

In many countries, turning off the Internet completely is not technically difficult. Regulators simply issue an order to telecom companies, telling them to shut off access or risk losing their licence.

In Kazakhstan, the events last month illustrate how an Internet shutdown can exacerbate an already chaotic situation. The technical roots of the shutdown go back to at least 2015, when the country tried to emulate its neighbours, China and Russia, which have for years practised Internet censorship. Authorities in those countries have developed methods for snooping on communications and built armies of hackers and trolls that can target opponents.

Last year, Russia slowed Twitter traffic during protests related to opposition leader Alexei Navalny, a delay that has continued. China has built an arm of the police to arrest those who speak out online and commands thousands of volunteers who post positive comments to cheer on government initiatives.

Kazakhstan authorities tried developing similar technical tools for surveillance and censorship without severing the key connections necessary for its economy to function, according to civil society groups and activists.

Last month, Kazakhstan plunged into disarray as anger over rising fuel prices grew into broad demonstrations, leading to a Russia-led military intervention. As the government cracked down, the protests turned violent. Dozens of anti-government demonstrators were killed, and hundreds more were injured.

To prevent protesters from communicating and sharing information, Kassym-Jomart Tokayev, Kazakhstan's president, turned to a digital scorched-earth policy akin to one in Myanmar last year that took the entire Internet offline. In Myanmar, the military staged a coup, and soldiers took over the data centres run by the country's telecom companies.

In Myanmar and Kazakhstan, the lack of Internet heightened the confusion. In the event of a conflict in Ukraine, that added confusion would be a part of the point, Klimarev said.

"Destroy the Internet of your enemy, and it will be disorganised," he said. "Banks, supply systems and logistics, transport and navigation will stop working."

In Kazakhstan, the Internet shutdowns began around Jan 2 and lasted until Jan 10. At first, they were limited to certain communications and targeted at areas where there were protests, said Arsen Aubakirov, a digital rights expert in Kazakhstan.

By Jan 5, Internet monitors said that the country had gone almost completely offline, battering the country's economy, including its sizeable cryptocurrency operations.

The Ministry of Digital Development, Innovation and Aerospace Industry ordered telecom operators to block access, citing a law that allowed the government to suspend networks and communication services in the interest of "ensuring anti-terrorist and public security".

While activists found some ways to circumvent the blocks, the lack of Internet meant many demonstrators did not know when the government imposed new curfews, leading to violent clashes with the police, said Sharipov, who was detained by the authorities for protesting. While the Internet was down, state-run media labeled the demonstrators "terrorists" and drug users.

"This is another example of a country in turmoil opting to shut the Internet down to buy them a few hours of lack of public or international scrutiny," Madory said.