Finland and Sweden want to join NATO. Here's how it works and what comes next

 https://edition.cnn.com/2022/05/14/europe/sweden-finland-nato-next-steps-intl/index.html

Finland's neutrality has historically proved more difficult, as it shared a massive border with an authoritarian superpower.

A Finno-Soviet treaty known as the Agreement of Friendship, signed in 1948 and extended on occasion through the decades, prohibited Finland from joining any military alliance considered hostile to the USSR, or from allowing a Western attack through Finnish territory.

To keep the peace, Finns adopted a process some call "Finlandization," in which leaders acceded to Soviet demands from time to time. The term was coined during the Cold War and has been applied to other countries in which a superpower exerts control over smaller neighboring states.