This will be inherently inaccurate because data was based on public AIS signal, but ships are turning off their AIS to avoid detection. > In an attempt to evade detection, many ships appear to be deliberately switching off their tracking system - known as AIS (Automatic Identification System). https://www.bbc.com/news/articles/c4geg0eeyjeo
Ships had their AIS on before the war, and will turn it on again once they left the area. So we can just filter for ships which previously reported a location in the Persian Gulf, and now are reporting outside of it. Similarly we can count ships which were outside of the Gulf and now are inside. We don’t need the AIS to be on while they are transiting.