The North Atlantic Treaty Organization, also known as the North Atlantic Alliance and often abbreviated to NATO, was a pre-War intergovernmental military alliance based on the North Atlantic Treaty.
Due to the divergence, the date of formation for NATO is left unclear. It most likely formed in 1949 in a similar, if not identical, way as it did in the real world. The nations of NATO were key players in the Cold War, representing the western bloc. It was hoped that the organization would counter the military power of the USSR and prevent the revival of nationalist militarism.
NATO issued a standard 7.62mm round, which was used in weapons of member countries.
The European Civil War and the simultaneous conflict in North America violate Article 1 of the North Atlantic Treaty. This suggests that the alliance disbanded sometime prior to or during the Resource Wars.
For more information on the organization's real world counterpart, see NATO on Wikipedia.