Wikipedia contributors. (2024, February 23). 2023. In Wikipedia, The Free Encyclopedia. Retrieved February 24, 2024, from https://en.wikipedia.org/w/index.php?title=2023&oldid=1209703169
Finland became a member of NATO on 4 April 2023, though it participated in the NATO Response Force before becoming a member.
https://github.com/davepinch/pinchy.cc/blob/master/content/topics/years/2023/en.wikipedia.org.snippet-april-4.md