When hundreds of video cameras with the power to identify and track individuals started appearing in the streets of Belgrade as part of a major surveillance project some protesters began having second thoughts about joining anti-government demonstrations in the Serbian capital.
Local authorities assert the system, created by Chinese telecom company Huawei, helps reduce crime in the city of two million. Critics contend it erodes personal freedoms, makes political opponents vulnerable to retribution and even exposes citizens to snooping by the Chinese government.
The cameras, equipped with facial recognition technology, are being rolled out across hundreds of cities around the world, particularly in poorer countries with weak track records on human rights.
With Washington claiming Beijing can get backdoor access to Huawei data, the rollout is raising concerns about the privacy of millions of people in countries with little power to stand up to China.
"The system can be used to trail political opponents and monitor regime critics, which is completely against the law,'' says Serbia's former commissioner for personal data protection, Rodoljub Sabic.
Groups opposed to Serbia's President Aleksandar Vucic say police are leaking video of protests to pro-government media, which publish the images along with the identities of participants. Vucic himself has boasted the police have the capability to count "each head" at anti-government gatherings.
Serbian police deny any abuse of the Huawei system, which will eventually encompass 1,000 cameras in 800 locations throughout Belgrade.
Some countries are reconsidering using Huawei technology, particularly the superfast 5G networks rolling out this year. But Huawei has no trouble finding customers eager to install its Safe Cities technology, particularly among countries that China has brought closer into its diplomatic and economic orbit.
Besides Serbia, the list includes Turkey, Russia, Ukraine, Azerbaijan, Angola, Laos, Kazakhstan, Kenya and Uganda, as well as a few liberal democracies like Germany, France and Italy. The system is used in some 230 cities.
In a promotional brochure, Huawei says its technology can scan over long distances to detect "abnormal behavior" such as loitering, track cars and people, calculate crowd size and send alerts to a command center if it detects something suspicious.
In one case advertised on its website the firm says a suspect in a Belgrade hit-and-run was discovered in China with the help of face-recognition data shared by Serbian police with Chinese counterparts.
In view of the cybersecurity accusations leveled by US and international rights groups against Huawei, ties between China and countries that use the company's technology are under renewed scrutiny.
China's influence in Serbia has expanded significantly in recent years through Beijing investment programs. The populist Serbian regime has been keen to develop closer ties, and the country's fragile democracy allows China's economic interests to grow relatively unchecked.
China's state investment bank has granted billions of dollars in easy-term loans to build coal-powered plants, roads, railroads and bridges. Chinese police officers even help patrol the streets of Belgrade - a presence billed as assisting the growing number of Chinese tourists.
It's a similar story in Uganda.
When President Yoweri Museveni launched a US$126-million (HK$980 million) project to install Huawei facial recognition systems last year he said the cameras were "eyes, ears and a nose" to fight crime in the capital, Kampala. Opposition activists say the real goal is to deter street protesters against an unpopular government.
In neighboring Kenya, the government has also renewed its focus on public safety after a spate of extremist attacks. It has been pushing to register people digitally, including by recording DNA, iris and facial data. To do so, it turned to China, which helped finance the installation of surveillance cameras as far back as 2012.
Back in Belgrade's downtown Republic Square, high-tech video cameras point in all directions from an office building. But "we don't want to be in some kind of Big Brother society,'' says rights activist Ivana Markulic.