It follows a decision by the Spanish government to deny the US use of the two jointly run military bases in Andalusia.
Archived version: https://archive.is/newest/https://www.bbc.com/news/articles/cwy368j1e3lo
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A friend of mine spotted a bunch of us war planes literally using Sofia airport in Bulgaria, so it’s an odd one that they use that flight path (but I have seen what you are talking about)