Under NATO’s 1949 founding treaty, decisions on enlargement are made “by unanimous agreement,” meaning that Fico’s opposition to Ukraine joining the alliance could indeed block its membership at least until the end of the Slovak leader’s current term in power in 2027. Other Russia-friendly NATO members could also seek to frustrate Ukraine’s membership aspirations.
On the subject of Slovakia, I agree to an extent. They were pushed to give Germany land in the late 1930s due to the Munich Agreement, which gave Nazis a foothold in the country itself. However, they quickly surrendered the rest of the country when the nazis said “Let’s have it”