Of course, the EU often ignores its own treaties. So that's not a hard guarantee. But the first rule of the EU is that everyone has to pretend it follows its own rules even when it doesn't, so it's not like Icelandic leaders can just announce they'll join the EU but won't adopt the Euro.
Of course, the EU often ignores its own treaties. So that's not a hard guarantee. But the first rule of the EU is that everyone has to pretend it follows its own rules even when it doesn't, so it's not like Icelandic leaders can just announce they'll join the EU but won't adopt the Euro.