https://github.com/ClickHouse/adsb.exposed/
I particularly like the example of helicopters following the river Thames in London:
https://github.com/ClickHouse/adsb.exposed/?tab=readme-ov-fi...
a) to make civilian air traffic control life easier
b) as (strategic) signalling - this applies for example to NATO tankers and electronic intelligence platforms flying over the Eastern Flank.
Remember, you want your opponent to know how you can potentially hurt them if things go bad, that's the basis of deterrence. This is why for example certain aspects of nuclear weapon systems are completely out in the public.
c) Safety, being open about the flightpaths of tankers and intelligence-gathering aircraft flying in international airspace near those areas reduces the ability of Russia to claim they weren't informed or that the aircraft strayed into restricted airspace. That means a lower probability of incidents, though it's still not completely safe as demonstrated in 2022: https://www.bbc.com/news/uk-66798508