The formation of the military alliances was the direct result of the tension between the East and the West produced by the Cold War.
(i) Treaty of Dunkirk (March 1947) and treaty of Brussels (March 1948)
Immediately after the Second World War, the western European nations felt threatened by the military power of the Soviet Union because she had emerged from the war stronger than she had been before it.
She had an annexed population of about 23 millions and an annexed area of over 180,000 square miles. Moreover, she had more than 3 million men under arms. Undoubtedly, Russia became the strongest military power in Europe.
In response to this military threat, Britain concluded a military alliance with France, known as the Treaty of Dunkirk. The chief purpose was to prevent future German aggression. It also provided for economic assistance and military co-operation against the political threat of the other aggressors, such as Russia.
The Prague Coup of February 1948 gave new fear of the Russian threat. Bevin, the British Foreign Secretary, immediately called for greater economic and military co-operation among the western European countries.
The Treaty of Dunkirk was broadened to include the Benelux countries – Belgium, the Netherlands and Luxemburg – and they signed the Treaty of Brussels. The Treaty of Brussels was not only a military alliance but also an ideological alliance. It provided for collective self-defence, economic and social collaboration in Western Europe.
(ii) The North Atlantic Treaty Organisation (NA.T.O.) (April 1949)
The five western states were increasingly suspicious of the Russian intentions in Europe since the Berlin Blockade. The United States also wanted to find allies in Europe to contain communist expansion.
On April 4, 1949, twelve nations – the United States, Canada, Iceland, Denmark, Norway, Portugal, Italy, Britain, France, Belgium, the Netherlands and Luxembourg signed the North Atlantic Treaty in Washington. (The Brussels Treaty was not dissolved.) The partners of the Treaty believed that Russian Communism, an anti-democratic ideology, had posed a new threat to the democratic world.
Thus they stated that “an armed attack against one or more of them shall be considered an attack against them all.”
In the event of such an attack, for the preservation of peace and their civilized way of life, they promised to take whatever action deemed necessary, including the use of armed force. This regional security arrangement for the defence of the North Atlantic area was valid for 20 years.
As a result of this Treaty, the nations in Western Europe were drawn together under American leadership. The headquarters of NATO known as SHAPE (Supreme Headquarters of Allied Powers in Europe) was established at Paris. The most important organisation of the NATO was the Permanent Council. It was established in 1952.