Nineteenth century Afghanistan served as a strategic buffer state between British India and Czarist Russia. After the Bolshevik Revolution in 1917, Afghanistan and Russia developed closer relations. In 1919, King Amanullah ascended to the throne and he signed the first international treaty the "Treaty of Friendship" with the Russians.
On April 27, 1978, the government of President Daoud was replaced by the People's Democratic Party of Afghanistan, headed by Nur Mohammad Taraki. The Soviets welcomed and supported the new government. Catastrophic blunders of the new regime were threatening to destabilize the Communist government and the Soviets decided to invade Afghanistan in December 1979.