Poroshenko tells Deutsche Welle about Ukraine's NATO-related plans / Photo from DW

"Our position is to reform the country. We need at least six or seven years to meet the criteria. The world would be more secure if Ukraine had an opportunity to do that," Poroshenko told Deutsche Welle in an exclusive interview.

Poroshenko claims he believes Kyiv will eventually join NATO, despite recent skepticism from European leaders, including German Foreign Minister Frank-Walter Steinmeier, and Russia's objections to Ukrainian membership, Deutsche Welle wrote.

"We're a sovereign and independent state, and we do not ask the permission either from Russia or from anyone else. Our position is to reform the country, and we need at least six or seven years to meet the criteria. We should do the work, which is necessary for us, and only then we should ask the Ukrainian people and hold a referendum [to see if] the Ukrainians accept [NATO] and want to be a NATO member state in seven years' time," the president said.

In his words, accession to NATO was supported by about 16% of Ukrainians, and nowadays their share is about 60%.

Commenting on the position of Steinmeier who sees Ukraine's partnership with NATO rather than membership of NATO, Poroshenko said: "This is just a position of Steinmeier for the year 2015, and nobody knows what the position of Germany would be in the year 2022."

Poroshenko says he believes that NATO is the only effective security system today.