Question

1. what is the key principle of nato?

free trade between nations: members may trade with one another.
shared space exploration: all members will help to fund the international space station.
mutual defense: if one member is attacked, all other members will defend them.
monitoring air traffic: members must share intelligence gathered by air intelligence.

Explanation:

NATO (North Atlantic Treaty Organization) is a military alliance. Its key principle is mutual defense. This means that if one member state is attacked, the other member states will come to its defense. This is enshrined in Article 5 of the North Atlantic Treaty. Free trade is more related to economic organizations like the World Trade Organization. Shared space exploration is not the main focus of NATO. Monitoring air traffic and sharing air - intelligence is a more specialized and not the core, overarching principle of NATO.

Answer:

Mutual defense: If one member is attacked, all other members will defend them.