The 19 kilometres long bridge is the only direct way linking the Russian mainland with annexed Crimea.

The whole project used up around USD 3.7bn and was done in disregard to the international community.

Reacting to it,  Ukraine's President Petro Poroshenko wrote in his Facebook page: "The illegal construction of the Kerch Strait Bridge is more evidence of Kremlin neglect of international law, especially the fact that the span was opened on the eve of another anniversary - the deportation of the Crimean Tatar people by the Stalin regime."

"Ukraine will continue to consistently defend its positions in the future. I recall that on my instructions to the Arbitration Tribunal of the UN Convention on the Law of the Sea. A petition was filed for the protection of Ukraine's sovereign interests, in particular, in connection with the illegal erection of the bridge.

"I'm sure the aggressor will not succeed. Russia will be fully responsible, and the bridge will be necessary for the invaders when they leave our Crimea urgently," he added.

Image: twitter.com/KremlinRussia_E