There will be more in the years to come if thanks to the current events. Plenty of people here and else where are quick to point out that Ukraine is in NATO and that Russia would not dare attack a nato country so this is all fine but at the end of the day NATO, like any treaty, is just a promise not inherently like the promise the Ukraine was made when they gave up their nuclear weapons. An attack on a NATO country will not mean an automatic response from all other NATO countries but instead prompt a decision from each of the leaders of those countries what would be better for their citizens at that point. Retaining their own protection via NATO is going to be a big influence of that decision but it is never going to be the only factor.