Heads of state and government of NATO member countries began sessions as part of the Madrid summit on Wednesday.
Speaking at the opening of the first session on Ukraine, NATO Secretary-General Jens Stoltenberg said important decisions will be taken to strengthen the alliance in a world where "authoritarian regimes" such as Russia and China are challenging the rules-based order.
Regarding the blueprint for NATO, the new Strategic Concept document, which will be approved in Madrid, Stoltenberg said allies will strengthen the deterrence and defense of the alliance while opening the doors to Sweden and Finland with a formal invitation.
According to the NATO chief, Ukrainian President Volodymyr Zelenskyy will deliver a speech to the leaders, and a comprehensive support package for war-torn Ukraine will be adopted.
Spanish Prime Minister Pedro Sanchez said the decisions that the allies take "will determine our capacity and use of our resources for the next 10 years. The world is watching us."
Congratulating Türkiye, Finland and Sweden on the signing of a trilateral memorandum to address Ankara's security concerns, Sanchez said: "The entry of these two countries into NATO will be an important turning point."