That was immediately after getting formal guarantee by the UK that in case of an attack, the UK will immediately defend Sweden (which weakened the need to join NATO substantially).
"Sverige ingår i samma familj, så vi skulle hjälpa Sverige. Vi skulle göra allt vi kan, både militärt och på andra sätt” "
"Britternas, nu officiellt uttalade militära stöd till Sverige..."
https://www.thelocal.se/20220304/britain-promises-military-a...
https://en.wikipedia.org/wiki/Budapest_Memorandum_on_Securit...
Shows exactly how much international agreements are worth: One of the countries that signed the agreement was Russia.
Muahahahahaa... Maybe as recently as the late 1970s or even, at a stretch, early-to-mid 1980s. But after that, newsflash for you: Sweden pretty much got rid of its erstwhile impressive defense.