Which of the following best describes the North Atlantic Treaty Organization (NATO)?

The description of NATO as a military alliance aimed at collective defense against aggression is accurate and encapsulates the primary purpose of the organization. Established in 1949, NATO's fundamental tenet is collective defense as outlined in Article 5 of the North Atlantic Treaty, which states that an armed attack against one member is considered an attack against all members. This principle forms the backbone of NATO’s operations and its commitment to deterrence and defense.

NATO's role has historically involved responding to external threats, and its military capabilities are integral to its identity as a defense alliance. The alliance has adapted over the decades to address various security challenges, including not only state aggression but also terrorism and cyber warfare.

The other choices do not accurately represent NATO's mission and activities. For instance, while NATO can apply economic sanctions through its member countries, this is not its primary focus; military readiness and collective defense take precedence. Similarly, NATO is not merely a peacekeeping organization; though it may engage in peacekeeping missions, it possesses robust military capabilities intended to defend its member states. Lastly, while diplomatic discussions occur within NATO, the organization is more than just a forum for diplomacy, as it actively engages in defense planning and operations.