Nato leaders decided at a summit in April against rapidly granting membership to Ukraine and Georgia, but the alliance said it would consider the prospect of taking in the ex-Soviet republic in the future.
Moscow has opposed the Western military alliance's expansion eastward, arguing that it is aimed at containing Russia.
Ukraine, which has a large ethnic Russian minority, has sided with Georgia in its confrontation with Russia over the breakaway region of South Ossetia.
Kiev watched with concern as Russia sent tanks and troops deep into Georgian territory in response to a Georgian offensive on August 7 to retake South Ossetia, whose separatist leadership is backed by Moscow.
Angela Merkel, the German chancellor, this month underscored the fact Nato's offer to Ukraine and Georgia to eventually join the alliance was still valid, despite the conflict in the Caucasus.