MOSCOW (AP) — Russian President Vladimir Putin is marking the fifth anniversary of Russia's annexation of Crimea from Ukraine by visiting the Black Sea peninsula.

Putin on Monday attended the launch of new power plants in Crimea, part of Moscow's efforts to upgrade the region's infrastructure. Ukraine has cut off energy supplies to the peninsula and blocked shipments of Crimea-bound cargo via its territory after Moscow annexed the region in 2014.

Russia's modernization effort has included the construction of a 19-kilometer (11.8-mile) bridge across the Kerch Strait linking the Black Sea and the Sea of Azov that opened last year. The $3.6-billion project helped facilitate links with Crimea, which previously depended on a ferry crossing that was often interrupted by gales.

Russia annexed Crimea in March 2014 following a hastily called referendum, a move that drew U.S. and EU sanctions.