surveillance mechanisms were mass camera surveillance on the streets, internet surveillance, and newly invented surveillance methods based on social credit and identity. As of 2018, the Chinese central government had also adopted facial recognition technology, surveillance drones, robot police, and big data collection targeting online social media platforms to monitor its citizens. In 2019 NSA whistleblower Edward Snowden said China's mass surveillance mechanisms and machinery of private communications was "utterly mind-boggling". As of 2019, it was estimated that 200 million monitoring CCTV cameras of the "Skynet" system had been put to use in mainland China, four times as many as the surveillance cameras in the United States. State media in China claim that Skynet is the largest video surveillance system in the world, utilizing facial recognition technology and big data analysis. In 2019, Comparitech reported that 8 out of 10 most monitored cities in the world are in China, with Chongqing, Shenzhen and Shanghai being the world's top 3. In 2019, China supplied surveillance technology to most of the world, and positioned the country in control over the mass surveillance industry. According to industry researcher IHS Markit, at the end of 2019 there were 770 million surveillance cameras in the world, with approximately 415.8 million of them located in China. If these trends continue, by the end of 2021 there will be about 1 billion in the world and 540 million in China. The government says this prevents crime, but citizens worry that their data and privacy could be compromised. In late October 2020, Deng Yufeng, an artist, used performance art to highlight how difficult it is to dodge the view of security cameras. Timeline In 2011, the Beijing Municipal Science & Technology Commission proposed a mobile phone tracking program, to be called the Information Platform of Real-time Citizen Movement, which was ostensibly intended to ease traffic flow on the city's streets. In the four years up to 2012, 100,000 crimes had reportedly been solved with the aid of surveillance cameras in Guangdong according to officials. However, a critic said that "one of the most important purposes of such a smart surveillance system is to crack down on social unrest triggered by petitioners and dissidents". In 2013, the government saw the severe atmospheric pollution in Chinese cities as a security threat because the closed-circuit television cameras were rendered useless. In December 2013, the Vice Minister of the Ministry of Industry