The Russian government approved plans on July 6 to build a bridge connecting the Russian mainland to the Crimean Peninsula.

Reports from earlier this year said the 12-mile bridge will span the Kerch Strait through the Tuzla spit, which divides Russia’s Krasnodar region from Crimea. The design will accommodate a railway and four lanes of automobile traffic. At an estimated cost of $4 billion, it will be the most expensive bridge Russia has ever built. Completion is expected by December 2018.

The Crimean Peninsula was Ukrainian territory until last March, when it was absorbed into the Russian Federation. The absorption happened after covert Russian forces had occupied government buildings in Crimea, and later supervised a referendum on whether the people of the peninsula wanted to join Russia or not. Moscow claims that 96.8 percent voted in favor of union with Russia.

The bridge project could allay concerns among some Westerners who speculate that Russia wants to annex regions of eastern Ukraine in order to make a “land bridge” connecting Crimea to mainland Russia. With plans now approved to build an actual bridge over the water, Russia would have a connection to Crimea without needing to pry away other territories from Ukraine.