NATO recognizes Ukraine and 3 others as aspirant countries (Source: ukrinform.net)

Currently, four partner countries have declared their aspirations to NATO membership: Bosnia and Herzegovina, Georgia, the former Yugoslav Republic of Macedonia and Ukraine. 

The status of aspirant countries means that countries that have declared interest in joining the Alliance are first invited to join the Intensified Dialogue with NATO regarding their desire for membership and related reforms.
Former NATO Secretary General, Anders Fogh Rasmussen said Ukraine have to reach the criteria set by NATO to become a member of this organization, which hard to be completed in 20 years.