The meeting in Brussels was called by Turkey, which has become involved in the Syrian conflict in recent days.
The country, which had previously been reluctant to intervene, has launched raids against IS in Syria and Kurdish PKK guerrillas in northern Iraq.
The strikes followed a wave of attacks by militants on Turkish soil.
Turkey, a key NATO member, called Tuesday’s meeting of the North Atlantic Council under Article 4 of the alliance’s founding treaty.
The clause allows members to request a summit if their territorial integrity or security is threatened.
It is only the fifth time in the alliance’s history that a member state has requested such a meeting.
It will give Turkey’s NATOlies the opportunity to work out its goals and motivation, after the country has stood on the sidelines of the Syria conflict for so long.