WARSAW — During her recent visit to Latvia, Chancellor Angela Merkel of Germany assured the Baltic states of German and NATO solidarity with them in the face of a potential armed conflict between Ukraine and Russia. As President Obama did earlier here, Ms. Merkel assured her audience that NATO’s obligations did not exist “only on paper.” She is expected to repeat that promise on Saturday, when she is scheduled to appear in Kiev.

Any assurance that something is indeed binding merely reflects the existence of doubts. In this case, the uncertainty is based on the absence of NATO soldiers in the alliance’s new member states, including Poland and the Baltics, which feel threatened as they observe Russia’s destructive actions in the region.

That absence is a longstanding concession to Russia, which fears NATO encroachment — one of the few remaining forms of control that Russia exercises over its former satellites. With the passage of time, this surrender of logic to geopolitics is becoming increasingly incomprehensible. Why should a country that is not party to NATO exercise any influence over it?

There is no need to pretend: Those members who have no NATO bases are simply a gray area of second-class membership. What has become clear is that not all NATO members are equal. First-class members — Britain, Germany, Italy — are those everyone knows would be immediately defended by NATO forces if attacked. Second-class members like Poland and the Baltics would most likely be ravaged for weeks or months before NATO forces made an appearance.