Icelandair is warning travelers they can't use the country as a backdoor into Europe

• Iceland is opening to vaccinated American tourists, one of the first European countries to do so.
• Americans without residency in the Schengen Area, however, can't travel onward to Europe.
• Travel between Iceland and many European countries was once as easy as traveling between US states.

The nation of Iceland is opening to vaccinated American travelers but that's as close to Western Europe as many US citizens will get, for now.

Icelandair, the country's flag carrier airline, is warning Americans that they will not be allowed to fly the airline to other European nations from Iceland, even though Iceland is in the European free movement area known as the Schengen Area.

"Iceland is welcoming vaccinated visitors from outside the Schengen zone, but further travel from Iceland to the rest of Europe is currently not permitted for non-Schengen residents," Icelandair's website states.

There are some exceptions as Croatia remains open to Americans the arrive with a negative COVID-19 test, according to the US Embassy in Croatia, and Malta will let in Americans that have spent at least two weeks in an approved country, according to the US Embassy in Malta, of which Iceland is one.

The Schengen Area is the reason travelers can move between most European countries without going through border checks each time. Similar to going from state to state in the US, a traveler could theoretically drive from Portugal to Estonia's border with Russia and not have to produce a passport when crossing the multiple national borders along the way.

Countries can, however, temporarily enact border controls in response to extraordinary circumstances. The COVID-19 pandemic saw temporary border controls enacted across the continent as nations went under lockdown.

Iceland's membership in Schengen has greatly benefited transatlantic travelers by reducing the time spent at passport control upon arrival in mainland Europe. Travelers from North America clear passport control at Iceland's Keflavik International Airport when bound for another Schengen country and their next flight is treated as a domestic flight.

So for vaccinated travelers wondering if they can enter Europe from Iceland, the answer is no. At least for now, Europe is largely closed to Americans as America is to Europeans.