After being demilitarized in 2005, Sweden re-introduced permanent troops to Gotland in 2016, following Russia’s annexation of Ukraine’s Crimean Peninsula in 2014. Sweden also became NATO’s newest member in March — meaning it is covered by the alliance’s Article 5 guarantee that all other members come to each other’s defense if they are attacked.
Given Putin’s long history of violating Swedish airspace over Gotland, I feel like the statement has at least some amount of credibility.
In fact, I would not be surprised if that is a large part of why public sentiment finally swayed in favour of NATO in Sweden after so many years of public sentiment being against the prospect.