West Germany Joins NATO and the Warsaw Pact
Also called: Warsaw Pact, Paris Agreements
When West Germany regained sovereignty and joined NATO, the Soviet Union, East Germany and the other Eastern European states formed the Warsaw Pact five days later. The two Germanys became the front line between two military blocs.

Bundesarchiv, B 145 Bild-P098967 / o. Ang. · CC BY-SA 3.0 de · Source
After the Korean War the Western powers pressed for West German rearmament. Under the Paris Agreements of 1954 the occupation ended and the Federal Republic regained its sovereignty on 5 May 1955; it joined NATO on 9 May and founded the Bundeswehr that year. Adenauer held that ties to the West must come before unity.
On 14 May in Warsaw the Soviet Union and seven Eastern European states signed the Treaty of Friendship, Cooperation and Mutual Assistance (the Warsaw Pact); East Germany was a founding member and set up its National People’s Army the next year. That year West Germany adopted the Hallstein Doctrine, threatening to break off relations with any state that recognized East Germany.