NATO's secretary-general has praised the role of Gulf nations in helping to fight extremists in Syria and Iraq, and says tackling the threat will require long-term multinational efforts.

Secretary-General Jens Stoltenberg made the comments Thursday during a visit to Qatar to mark the 10-year anniversary of the Istanbul Cooperation Initiative, a partnership between the alliance and several Gulf states.

He says it is important Qatar and other countries are involved in fighting extremists because of the military capabilities they can offer and to show "this is not about the West imposing its will on others."

A number of Arab nations, including Saudi Arabia and the United Arab Emirates, have taken part in air strikes against the Islamic State group. Others such as Qatar are playing a supporting role.