Ukraine's President Petro Poroshenko has said that Ukraine will only be able to join NATO after the country has implemented all the necessary reforms.

"Now it is my responsibility to provide and implement reforms in my country, to transform the country to NATO [standards], and then we will have this discussion. I think I need for that at least five, six years," Poroshenko said in an interview with CNN when asked about potential Ukrainian membership of NATO.

He said that the issue of security is extremely important for Ukraine which is itself a target of aggression.

"NATO today is maybe the only most effective mechanism to provide security," Poroshenko said.