The North Atlantic Treaty Organization (NATO) is the intergovernmental military alliance based on the North Atlantic Treaty. This treaty was signed in 1949. The headquarters is the NATO is at Boulevard Leopold III in Brussels, Belgium. 

It is through NATO, the United States entered into a peacetime military alliance outside of the Western Hemisphere for the first time. After the Second World War, the European countries struggled to rebuild their economies and ensure their security.

The economically strong United States rearmed and integrated Europe to prevent communist expansion across Europe. Even though World War 2 had come to an end, the United States and the USSR starts Cold War. 

The Treaty of Brussels was signed on 17 March 1948. It was signed by Belgium, Netherlands, Luxembourg, France, and the United Kingdom. The Treaty of Brussels is considered the precursor to the NATO agreement. Western European Union was a military alliance was established by this treaty. 

North Atlantic Treaty was signed in Washington, DC on 4 April 1949. It was a result of the talks for the military alliance. The North Atlantic Treaty included the five Treaty of Brussels states, United States, Canada, Portugal, Italy, Norway, Denmark and Iceland. On 18 February 1952, Greece and Turkey also joined. 

NATO Members

NATO has 30 member countries. Montenegro was its newest member. NATO Member Countries are 

The United Kingdom (1949)

France (1949)

Netherlands (1949)

The United States (1949)

Germany (1955)

Norway (1949)

Denmark (1949)

Luxembourg (1949)

Belgium (1949)

Portugal (1949)

AIceland (1949)

Canada (1949)

Italy (1949)

Greece (1952)

Turkey (1952)

Spain (1982)

Poland (1999)

Hungary (1999)

Czech Republic (1999)

Bulgaria (2004)

Latvia (2004)

Romania (2004)

Slovakia (2004)

Slovenia (2004)

Lithuania (2004)

Estonia (2004)

Croatia (2009)

lbania (2009)

Montenegro (2017)