In 2017 Copenhagen had a wave of gang shootings with 1-2 daily fatalities during the worst weeks. That is nothing compared to the most violent US cities but it was completely unprecedented for a Danish city.
The gang warfare was stopped by massive police surveillance operations. This included military surveillance and signal intelligence planes [1] and helicopters to aid the police.
It worked. I know it goes against left-libertarian talking points on HN/reddit to suggest that police and surveillance can actually stop crime but it did in 2017 in Copenhagen.
Looking at the gang problems still facing Sweden I'm fine with Danish authorities going full surveillance mode back in 2017 instead of letting the gang violence grow to Swedish levels.
[1]: https://www.berlingske.dk/samfund/politiet-tager-nye-vaaben-...