The Dutch spy service broke into computers used by a powerful Russian hacking group and may be sitting on evidence relating to the breach of the US Democratic National Committee, reports say.
Respected daily newspaper Volkskrant and TV current affairs show Nieuwsuur said hackers working for the Dutch General Intelligence and Security Service penetrated the computers used by the group, often nicknamed Cosy Bear, in mid-2014 and watched them for at least a year, even catching them on camera.
Dutch officials declined to comment.
Interior minister Kajsa Ollongren, interviewed by reporters in The Hague before the government’s weekly cabinet meeting, said she was "very happy that we have good security services in the Netherlands that do their work well. I can’t say anything about this case that has been published".
Volkskrant and Nieuwsuur said the Dutch spies used their access to help oust Cosy Bear from US State Department computers in late 2014.
Volkskrant said American spies were so grateful they sent the Dutch cake and flowers.
Cosy Bear was later identified as one of two Russian government-linked hacking groups that broke into the DNC ahead of the 2016 presidential election. The other is usually called Fancy Bear.
Cybersecurity firm CrowdStrike said the two groups operated independently.
Unmasking the Cosy Bear hackers would provide key evidence for investigators trying to unravel the DNC breach, but it may not dispel the mystery surrounding the leaks that followed.
A recent AP investigation found that all but one of the two dozen or so officials whose emails were published in the run-up to the 2016 election were targeted by Fancy Bear, suggesting a separate Russian intelligence operation may have been responsible.