Russian President Vladimir Putin travelled to Crimea on Friday to mark the second anniversary of the peninsula's annexation and inspect construction of a bridge meant to link it to mainland Russia.

Russia's annexation of Crimea, followed by a Moscow-backed rebellion in eastern Ukraine, prompted the West to impose economic sanctions against Russia that, along with slumping oil prices, contributed to the sharp devaluation of Russia's currency. Russia annexed Crimea in 2014 after a hastily organized referendum not recognized by the United States and the European Union. Even Russian allies like Belarus refused to recognize it.

Across Russia, pro-Kremlin groups held rallies to mark two years since Crimea's self-proclaimed leader signed the treaty to join Russia.

Putin began his trip Friday by visiting the construction site for the 19-kilometer bridge across the Kerch strait that will link the peninsula with southern Russia. Following a blockade that Ukrainian volunteers imposed on the peninsula from the de-facto Ukrainian border, the Ukrainian government last year barred all commercial transport from crossing into Crimea on the Ukrainian strip of land. Since then, cargo is delivered to Crimea either by plane or by ferry across the strait.

Building the bridge to Russia is a "historic mission", Putin told the construction workers in remarks reported by Russian news agencies.

The $3 billion contract to build the bridge was awarded to the company owned by Putin's judo sparring partner Arkady Rotenberg.