North Korea laundered $147.5 million through virtual currency platform Tornado Cash in March after stealing it last year from a cryptocurrency exchange, according to confidential work by United Nations sanctions monitors that Reuters saw on Tuesday.

The monitors told a U.N. Security Council sanctions committee in a document submitted on Friday that they had been investigating 97 suspected North Korean cyberattacks on cryptocurrency companies between 2017 and 2024, valued at some $3.6 billion.

That included an attack late last year where $147.5 million was stolen from the HTX cryptocurrency exchange before being laundered in March this year, the monitors told the committee, citing information from crypto analytics firm PeckShield and blockchain research firm Elliptic.