Ukraine may join NATO in four years, Ukrainian Defense Minister Gen. of the Army Viktor Muzhenko said in Tallinn on Friday.

"In keeping with Ukrainian President Petro Poroshenko's directive, the armed forces must be ready for this in 2020. We are well capable of meeting this target," Muzhenko said on Estonian television.

"The Ukrainian armed forces have gained the necessary combat experience and are actively preparing at the moment for possibly joining NATO," he said.

"There are still a lot of technical issues concerning modifications of weapons and hardware. There is also an issue of the unification of training practices. Some doctrinal documents are lacking. That is, there is still a lot of room for such activities," Muzhenko said.

Estonian defense forces Commander Lt. Gen. Riho Terras vowed to support Ukraine in its NATO aspirations but declined to guarantee that it will become an alliance member in 2020.

"We will hold staff negotiations at the start of next year, where we will be able to discuss cooperation in defense planning in detail," Terras said.