President Vladimir Putin.
On March 17, 2014 President Vladimir Putin signed Executive Order On Recognizing the Republic of Crimea.
The Executive Order reads, in part:
“Given the declaration of will by the Crimean people in a nationwide referendum held on March 16, 2014, the Russian Federation is to recognise the Republic of Crimea as a sovereign and independent state, whose city of Sevastopol has a special status.”
The Executive Order comes into force on the day of its signing.
Source: Kremlin.ru