The report, by researchers Victor Cha and Joseph Kim, divides the workforce into three categories. The estimate of up to 12,000 North Korean citizens at the facility comes from Ukrainian military intelligence and is cited in the report.

North Korean workers are paid about $2.5 an hour, with 70% to 90% of their earnings taken by the state that sent them, according to the report. The Multilateral Sanctions Monitoring Team (MSMT) estimates that a North Korean worker receives an average of $7,500 a year, most of which is confiscated by Kim Jong Un's regime.

The second group is made up of girls aged 16 to 22 from Africa, Asia and Latin America. They are recruited through social media and Telegram with promises of service-sector work paying from $500 a month, or of training. On arrival their passports are taken and they are charged debts for their flights and accommodation, after which about 90% are sent to assemble drones and work with chemicals.

The third category is students of the Alabuga Polytechnic college. They are drawn into production from the age of 15 under the guise of practical training, shifts last up to 12 hours, and fines are imposed for disclosing information.

"The salaries of North Korean workers are confiscated by the state that sent them. This is the very definition of forced labor," the report's authors write.

According to the researchers, the plant can produce more than 5,500 drones a month. Ukrainian intelligence estimates that its staff is to be expanded from about 1,000 to 40,000 people, and in 2026 Russia expects to produce up to 60,000 drones. Chinese components account for about 80% of the critical electronics in Russian drones, including engines, batteries and navigation systems.

The report's authors call on the US Treasury to impose sanctions on companies and educational institutions involved in recruitment, block recruiters' social media accounts and pressure international companies operating in the special economic zone. They also propose creating a multilateral UN group to investigate.

According to MSMT data, between 35,000 and 100,000 people have been sent from North Korea to Russia and China in total, including to work in military production. Since 2022, Pyongyang could have earned up to $22 billion from its partnership with Moscow and Beijing, many times its foreign-currency income before Russia's invasion of Ukraine.