Answer:
 29 North American and European countries. Some of these countries are United States, Canada, England, Portugal, Spain, Italy, Germany, France, and others.
Step-by-step explanation:
 The NATO is an intergovernmental military alliance that constitutes a system of collective defense where its independent members agreed to mutual defense as a response of an external attack to any of them.
 The original alliance had 12 countries and was signed in 1949.
 I hope this answer helps you.