Two Ukrainian missiles have targeted a bridge linking Russia to the annexed Crimean peninsula, Moscow says.
Videos on social media show plumes of smoke rising near Kerch bridge. Russia`s defence ministry said S-200 missiles had been used and shot down causing no damage.
Ukraine has not commented on the alleged attack.
There have been at least two other attacks targeting the bridge in the past few months.
The Kerch bridge was opened in 2018 and enables road and rail travel between Russia and Crimea - Ukrainian territory annexed by Russia in 2014.
It is an important resupply route for Russian forces occupying parts of southern Ukraine.
Russia`s defence ministry said that Ukraine had targeted the structure on Saturday at around 13:00 (10:00 GMT).
It identified the missiles used as S-200s - guided, Cold War-era surface-to-air weapons originally designed to destroy enemy aircraft that have apparently been adapted for ground-attack use.
The country`s foreign ministry meanwhile said that "such barbaric actions... will not go unanswered".
Crimea`s Russia-appointed governor Sergei Aksyonov later said that a third rocket had been shot down over the Kerch Strait.
Earlier on Saturday, Russia said it had shot down 20 Ukrainian drones near the peninsula.
An adviser to Mr Aksyonov said that traffic was halted and the smoke was an intentional "screen" generated by the military.
While Kyiv has not confirmed the attack, nor the weapons used, it would be the latest in a number of Ukrainian attempts to damage the bridge.
Last month, the Ukrainian website Euromaidan Press claimed that converted S-200 missiles had been used to attack the bridge as well as two military targets in Russia`s Rostov and Bryansk Oblasts.
Also last month, two people died and another was injured when the bridge was struck by explosions.
Kyiv did not officially confirm it carried out the attack, but a source in its security service told BBC Russian it was behind it and that water-based drones had been used.
Ukrainian President Volodymyr Zelensky said afterwards that the bridge was a legitimate military target that supplied Russia`s war effort "with ammunition on a daily basis".
"Understandably, this is a target for us. And a target that is bringing war, not peace, has to be neutralised," he added.
An explosion on the bridge in October still remains a mystery.
Footage from the time showed a huge fireball erupting as a number of cars and lorries made their way across the bridge.
The bridge was partially closed and only fully reopened in February.
Kyiv has repeatedly said it plans to retake Crimea and all territories seized by Russia since it launched a full-scale invasion of Ukraine in February 2022.
An apparent increase in military operations around the bridge comes as Kyiv presses its summer offensive against Russian forces in the Ukraine`s east.
Mr Zelensky has conceded that advances have been "slower than desired" as his Western-equipped forces face Russia`s well-prepared defensive lines.
Moscow has also blamed Ukraine for a series of drone attacks on Moscow, including strikes on the Kremlin and a tower block housing government ministries.
While not officially confirming they were Ukrainian operations, Mr Zelensky said that "gradually, the war is returning to the territory of Russia ... this is an inevitable, natural and absolutely fair process."
Meanwhile, Russia continues to attack civilian targets in Ukraine, including deadly missile strikes that destroyed a blood transfusion centre in Kharkiv and a residential area in Zaporizhzhia in the last week.
