Article 5 of the North Atlantic Treaty states:

"The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.

Any such armed attack and all measures taken as a result thereof shall immediately be reported to the Security Council. Such measures shall be terminated when the Security Council has taken the measures necessary to restore and maintain international peace and security."

There are 30 member countries of the North Atlantic Treaty Organization (NATO), established by the North Atlantic Treaty, the full list of which can be found here: https://www.nato.int/cps/en/natohq/nato_countries.htm

This is a market on whether any NATO member country invokes Article 5 of the North Atlantic Treaty by June 30, 2022. If any NATO member country invokes Article 5 of the North Atlantic Treaty at any time between March 2, 2022, and June 30, 2022, 11:59:59 PM ET (inclusive), this market will resolve to "Yes". Otherwise, this market will resolve to "No".

The primary resolution source for this market will be official information from NATO (nato.int), however credible media sources will also suffice.