At the end of World War II, 80 million people were dead and huge parts of Europe and Asia were in ruins. During the war, the Soviets were allies of England and the U.S., but Josef Stalin had different designs for post-war Europe.
He was bent on expanding communism and his territory across Eastern Europe.
In March of 1948, a coup d'etat in Czechoslovakia flipped the switch. Western governments realized they needed a stronger line of defense — a firewall.
First Great Britain, France, Belgium, the Netherlands and Luxembourg signed the Brussels Treaty agreeing to collective defense. They wanted the United States' muscle behind them, too, and the U.S. pushed for the inclusion of Canada, Iceland, Denmark, Norway, Ireland and Portugal in a new treaty.
All 12 joined forces and made it official in April 1949, forming the North Atlantic Treaty Organization. The main objective: "To safeguard the freedom, common heritage and civilization of their peoples, founded on the principles of democracy, individual liberty and the rule of law."
The heart of NATO's strength is Article 5: All members pledge to come to each other's defense in times of war. An attack on one is an attack on all. The only time Article 5 has been invoked was after 9/11.
Within 24 hours, NATO countries declared their symbolic support. They eventually sent surveillance planes to guard U.S. skies, as well as troops to Afghanistan.
Today, NATO's grown to 29 member nations headquartered in Brussels. There's a secretary general and each member has a representative.
In 2014, NATO allies established a guideline to spend a minimum of 2 percent of their GDPs on defense by 2024, responding to "Russia's aggressive actions against Ukraine."
More recently, President Donald Trump criticized countries for not pulling their weight in military spending. A few nations are on track to hit the 2 percent goal. Others are straggling. Russia would like nothing more than to see NATO crumble.
But for now, member nations are still committed to protecting western security and democracy even if money remains a sore spot.