New York City's police department is monitoring citizens using cameras and facial recognition software developed in China.
The surveillance tools are identical to those used in Sky Net in China, the largest video surveillance system on Earth, Chinese government research institutes and a company involved in the project said.
At a time when China and the United States are locked in a rivalry on several fronts including trade and technology, Hikvision - which is the world's largest surveillance technology company and based in Hangzhou in eastern China - has supplied the equipment and software used by an American force that polices a population of about 8.6 million people.
It has been claimed that Hikvision's system can accurately identify faces regardless of race, whereas some Western-developed technology had previously been more accurate for white people than for black citizens - although the NYPD has not discussed its reasons for using the Chinese technology.
The Sky Net programme, now renamed Pingan Chengshi, or Safe Cities, claimed to have connected 170 million cameras across China last year. By 2020, another 400 million units will be installed, it said, casting a watchful eye on every two citizens. Beijing plans to be able to identify anyone, anytime, anywhere in China within three seconds.
One American community where the Sky Net-style technology has been rolled out is River Park Towers, in the Bronx, the northernmost of New York's five boroughs.
River Park Towers is one of New York City's largest government-subsidised housing developments for lower-income families. Completed in 1975, it has a chequered history of arson, drug rings and gang violence. Police tried to cut crime but were faced with accusations of heavy-handed stop-and-search tactics and home searches without warrants.
There were complaints alleging racist policing, according to US media reports, with officers accused of profiling African-Americans as criminals.
Thousands of Sky Net cameras, aided by artificial intelligence (AI) software, have monitored River Park since 2014, according to the Hikvision website.
Cameras equipped with infrared sensors and capable of capturing high-resolution facial images even in very low light were installed in entrances, lobbies, corridors and stairwells in an effort to defeat vandalism.
The Hikvision surveillance system was bought and installed by the River Park Towers property management company, and the NYPD had direct access to the network, according to an article in Security Products Magazine.
Officers could view footage remotely and observe suspects in detail without a conspicuous police presence, the article said.
In one instance, a young man wanted by the police entered the complex to see a friend.
His photo was in the computer database and facial recognition software triggered an alert to officers.
The cameras tracked the man's movements throughout the building. When he entered the lobby on the ground floor with his friend, he was arrested. The NYPD did not respond to enquiries about the technology by the South China Morning Post.
Hikvision's software, which can spot and follow a person by face, figure or gait, can accurately identify people of all skin tones.
Technology companies including Microsoft and IBM used mostly white models to train their AI.
In February 2018, a Massachusetts Institute of Technology study found that a Microsoft machine could recognise white males every time but had a margin of error of more than 20 per cent when used to identify a black woman.
Google, meanwhile, had apologised after its AI identified African Americans as "gorillas" in 2015.
In response to enquiries from the Post, Google said it was appalled by that mistake and had taken steps to fix it, although "like all systems, it's definitely not perfect".
The company said that its policy on AI dictated that it "will not design or deploy AI" for "technologies that gather or use information for surveillance violating internationally accepted norms".
Microsoft did not respond to enquiries about its technology.
Hikvision's surveillance technology does not have a racial bias, a member of Hikvision's technical team told the Post."
The facial recognition [technology] has been used in many areas," he said. "It works perfectly well in communities with a large black population."
The exact extent of the use of Chinese cameras and software in New York's network is unknown, but according to an official document drafted by Chinese authorities and seen by the Post, Hikvision products are used by the NYPD on a "large scale".
Liu Jing, a researcher for the National Laboratory of Pattern Recognition at the Chinese Academy of Sciences in Beijing, said that machine recognition of faces with dark skin tones had been a major challenge for artificial intelligence developers for years.
Solving the problem required "leaps and bounds in technology", said Liu, who was not involved in the Hikvision project.
The Hikvision technology originated in a joint study by researchers at Wuhan University in Hubei and the Xian Institute of Optics and Precision Mechanics in Shaanxi province, to improve the quality of nighttime surveillance footage, according to the document.
Low-light or infrared cameras could "see" things in a dark environment, but the images they produced were often distorted and unclear.
Chinese developers created an algorithm which, by learning from existing video data, could accurately assess details in a low-quality image, especially facial features.
After years of improvement, the system can now identify a person at night with "just a few stars blinking in the sky", another Hikvision engineer told the Post.
The technology works on people who have darker skin tones by lightening their complexion so that the machine was less likely to be confused by their skin colour, said the engineer."
It enables us to better focus on the differences in their facial features. The identification is almost instant and highly reliable," he said.
Hikvision products and technology have been used across the US, according to the Chinese government document. This includes the 3,813km (2369 mile) US Route 1, the United States' longest north-to-south road, connecting major cities on its east coast.
Major Chinese technology companies including Hikvision could become subject to potential US sanctions against China, after the White House and some US lawmakers accused some firms of involvement in the Chinese government's domestic suppression campaigns and threatened to cut off chip supplies to their factories.
Chinese surveillance products have relied heavily on advanced sensors and processing units built by American chip makers.
Hikvision did not respond to the Post's queries on this and other matters.
The NYPD was sued in May 2017 by the Centre on Privacy and Technology at Washington's Georgetown University after it refused to respond to Freedom of Information Act requests for details of its facial recognition programme.
The force has argued that doing so would undermine investigations and help criminals, according to a New York Daily News report last March.
When asked about the case by the Post, the office of the NYPD's deputy commissioner for public information said the force always had to balance people's private rights with public safety.
Numerous US federal government agencies - including the US embassy in Afghanistan and several US military bases - have stripped Hikvision cameras from their buildings in recent months, citing security concerns, according to US media reports.
However, the advances in surveillance would continue regardless of their switch of manufacturer, according to a professor at the School of Government at Peking University who studied the use of technology in governance."
The US government could pull all Chinese cameras off the streets and create business for American surveillance companies, and taxpayers would be willing to foot the bill," the professor, who requested not to be named, said. "But it does not change what they are doing.
"Beijing and Washington are in a race to be the world's biggest peeping Tom."
- South China Morning Post