The Milyukov note was an incident on the 20th of April 1917, one which resulted in the bolstering of support for the Bolsheviks in Russia, and a widespread mistrust of the Russian Provisional Government. The Bolsheviks, who had long thought that the Provisional Government was continuing the war in the same fashion that the Tsarist Government had, had little proof of this and were simply waiting for a time to take action in spreading popular mistrust of the Provisional Government.
Foreign Minister Pavel Milyukov sent the Allied Powers a telegram, one which would prove to be a turning point of 1917. The telegram contained the statement that the Provisional Government would continue the war with the Tsarist war aims. The telegram was leaked to the Bolsheviks by an insider, and they began protests against the Provisional Government, which had previously promised the people that the terror of Tsardom had ended.
Michael C Hickey writes "News of the Milyukov Note weakened the position of the right Kadets in Smolensk but had no effect upon the local constellation of political power, since socialists had already entered local administration in force".
Milyukov stepped down as Foreign Minister. This was a significant event in the increased popular support of the Bolsheviks, as they had exposed an inherent weakness in the Provisional Government: duplicity.