The 19-km bridge is the largest in Russian Federation built so far. "And finally, thanks to your work and your talent, the miracle has happened".
The president crossed the bridge driving the Kamaz truck. "Particularly cynical is the fact that its discovery comes on the eve of the anniversary of the deportation of the Crimean Tatar people by the Stalinist regime", - wrote Poroshenko.
The annexation of the peninsula in 2014 was condemned by Kiev and the West as an illegal land grab but applauded in Russian Federation.
Built at a cost of 223 billion roubles ($3.60 billion), the bridge will be the longest dual-purpose span in Europe.
The railway bridge is not yet finished and has a deadline of the end of 2019.
"Putin initiated this project himself. Many didn't believe these plans were possible", Kremlin spokesman told reporters on Tuesday ahead of the ceremony.
"This is an extremely important day from this point of view and in a practical sense and in symbolic terms".
In July 2017, the bridge's arch for road traffic was installed.
The Soviets managed to finish the bridge in the summer of 1944 using the materials left by the German army, but the bridge was destroyed six months later by ice flows.
Russian President Vladimir Putin on May 15 opened a 19-kilometer bridge across the Kerch Strait connecting the Russian-occupied Ukrainian territory of Crimea with Russia, an ambitious project completed some 75 years after the Nazis first tried to do the same.
The European Commission said in a statement that the building of the bridge was an "another violation of Ukraine's sovereignty and territorial integrity by Russian Federation", adding that the new bridge will also hinder the access of Ukrainian shipping to Ukrainian ports on the Sea of Azov. He was hit with sanctions by the USA for his proximity to Putin and by the European Union for being among those accused of undermining Ukraine's territorial integrity.