WASHINGTON (AP) — North Korean hackers have pilfered billions of dollars by breaking into cryptocurrency exchanges and creating fake identities to get remote tech jobs at foreign companies, according to an international report on North Korea’s cyber capabilities.

Officials in Pyongyang orchestrated the clandestine work to finance research and development of nuclear arms, the authors of the 138-page report found. The review was published by the Multilateral Sanctions Monitoring Team, a group that includes the U.S. and 10 allies and was set up last year to observe North Korea’s compliance with U.N. sanctions.

North Korea also has used cryptocurrency to launder money and make military purchases to evade international sanctions tied to its nuclear program, the report said. It detailed how hackers working for North Korea have targeted foreign businesses and organizations with malware designed to disrupt networks and steal sensitive data.

Despite its small size and isolation, North Korea has heavily invested in offensive cyber capabilities and now rivals China and Russia when it comes to the sophistication and capabilities of its hackers, posing a significant threat to foreign governments, businesses and individuals, the investigators concluded.

Unlike China, Russia and Iran, North Korea has focused much of its cyber capabilities to fund its government, using cyberattacks and fake workers to steal and defraud companies and organizations elsewhere in the world.