The Ukrainian diplomat expressed this opinion before a meeting of the Ukraine-NATO Council.
Kuleba said that Ukraine's victory in the conflict is in the interests of the entire Euro-Atlantic community.
He added that defending Europe without Ukraine is a waste of time.
"You won't be able to do it, simply because Ukraine has the strongest and most battle-hardened army in Europe," RIA Novosti quoted him as saying.
Earlier, Hungarian Foreign Minister Péter Szijjártó said that the foreign ministers of NATO countries during a meeting in Brussels admitted that the counteroffensive of the Armed Forces of Ukraine had failed.