According to Jens Stoltenberg, its secretary general Jens Stoltenberg, NATO membership is a “top priority” for Sweden and Finland.
The military alliance is expected to include both Scandinavian countries, but admissions were thwarted by Turkey and Hungary, two of the 30 members.
Turkey had agreed to Drop a Block on the Nordic Countries in June last year.
Protests in Ankara and Sweden erupted after a far-right activist burned a Koran outside the Turkish Embassy in Stockholm in January.
Stoltenberg stated that Turkey had agreed to resume discussions with Finland and Sweden about their respective membership bids in Brussels at the beginning of next month, and to resolve any problems.
The Nato chief spoke at a news conference alongside the Finnish Prime Minister Sanna Marina and stated: “I am absolutely certain that both Finland, and Sweden will become NATO members.”
Norway’s NATO member Stoltenberg said that the Hungarian Parliament had “made it clear” it would ratify the treaty within a few days. He hoped for a positive vote.
He stated: “My message was for a long while… it is now that the ratification process can be completed.” It is now that both Ankara and Budapest have to ratify.
He stated that both Scandinavian countries meet all the criteria for entry to NATO and have “performed what they were supposed” since they applied to join in May.
Ms Marin suggested that NATO’s slow accession process could lead to a loss of credibility and an open-door policy for potential new members.
NATO needs unanimous approval from all its members in order to accept new members.
The Finnish parliament is ready for approval of legislation allowing the country to join the organization.