The NATO-Ukraine commission has discussed the security situation in Ukraine, progress in defense reform implementation and NATO's support for the country in Brussels on Wednesday, NATO Secretary General Jens Stoltenberg said in his opening statement.

"We will prepare grounds for our meeting with [Ukrainian] President [Petro] Poroshenko at Warsaw summit. NATO still strongly supports Ukraine's sovereignty and territorial integrity," Stoltenberg said.

He also promised that NATO would continue helping Ukraine to improve its ability to protect itself.

Stoltenberg stressed that "transformation of the Armed Forces of Ukraine during the conflict in eastern Ukraine is a complicated task."

"However, we can see progress in the development of necessary framework for defense and security reforms. It is important to keep following the path of reforms for the sake of stability in Ukraine and security in Europe," Stoltenberg said.