North Korean university students swept top places at a hacking contest run by US-based software company HackerEarth in May, US broadcaster Radio Free Asia said on Thursday.

Students of the Kim Chaek University of Technology won first, third and fourth places with perfect scores in a coding marathon for developers called May Circuits 2023 in which some 1,700 people participated.

A student of the Kim Il Sung University won second place. Another Kim Chaek student finished 10th.

The HackerEarth website shows that the five North Korean students have been taking part in the Indian-owned company’s challenges since as early as 2016.

In the June Circuits, the Kim Il Sung University student won second place, and the Kim Chaek students came fifth, sixth and ninth.

Kim Chaek University of Technology said on its website that its students were making efforts to see greater progress in the programming competition next time, according to RFA. Access to North Korean websites is blocked in South Korea.

North Korea recruits and trains its hackers through Kim Il Sung University and Kim Chaek University of Technology where students learn computer science, and some of the best are recruited into the regime’s global hacking efforts, RFA said, citing IT experts such as Annie Fixler at the nonprofit think tank Foundation for Defense of Democracies.

The report also quoted Park Sung-soo, a researcher at Russian multinational cybersecurity and anti-virus provider Kaspersky, as saying that the performance of Korean language-based hacking groups has significantly improved recently.

The Wall Street Journal reported last month that North Korean hackers have stolen more than $3 billion over the past five years, with the US government saying a big share of that is being funneled into the country’s nuclear missile program.

According to US cybersecurity firm Recorded Future, an analysis of 273 cyberattacks linked to North Korean state-sponsored hacking groups over a 14-year period showed that information collection was the primary motivation for more than 70 percent of them.