Russian divers on Sunday will examine the damage left by a powerful blast on a road-and-rail bridge to Crimea, a key supply route to its forces fighting in southern Ukraine.
The explosion on the bridge over the Kerch Strait happened on Saturday. No one has yet claimed responsibility.
Divers were due to start work early on Sunday, said Russian Deputy Prime Minister Marat Khusnullin. A more detailed survey above the waterline was expected to be completed by the end of the day.
“The situation is manageable — it's unpleasant, but not fatal,” said Crimea's Russian governor, Sergey Aksyonov.
The peninsula had a month's worth of fuel and more than two months' worth of food, he added.
Russia's Defence Ministry said its forces in southern Ukraine could be “fully supplied” through existing land and sea routes.
On Sunday, freight trains and long-distance passenger trains were able to begin using the bridge again.
The bridge, which is critical for the Kremlin to resupply its forces in Crimea and in the Kherson region of Ukraine, was reopened just hours after its partial collapse.
“It is almost certain that some vehicle transits via the other two carriageways have resumed, but capacity will be seriously degraded,” the UK's Ministry of Defence said.
“Any serious disruption to its capacity will highly likely have a significant impact on Russia’s already strained ability to sustain its forces.”
Russia seized Crimea from Ukraine in 2014 and the 19-kilometre bridge linking the region to its transport network was opened with great fanfare four years later by President Vladimir Putin.
Kyiv demands that Russian forces leave the Black Sea peninsula, as well as Ukrainian territory they have seized since the invasion Mr Putin launched in February.
The bridge is a major artery for Russian forces that control most of southern Ukraine's Kherson region and for the Russian naval port of Sevastopol, whose governor told locals: “Keep calm. Don't panic.”
It is not yet clear if the blast was a deliberate attack, but the damage to such a high-profile structure came amid battlefield defeats for Russia, and could further cloud the Kremlin's reassurances that the conflict is going to plan.
On Saturday, Mr Putin signed a decree for tighter security at the bridge, as well as the infrastructure supplying electricity and natural gas to Crimea. He also ordered an investigation.
“Conceivably, the Russians can rebuild it but they can't defend it while losing a war,” said political analyst James Nixey of Britain's Chatham House think tank.
Russian officials said three people had been killed, probably the occupants of a car travelling near a lorry that blew up.
On the bridge's upper level, seven fuel tanker wagons also caught fire.
The Kerch bridge blast came a day after Mr Putin's 70th birthday, coinciding with Russia's third senior military appointment in a week, that of Air Force Gen Sergei Surovikin assuming charge of the invasion effort.
Ukrainian President Volodymyr Zelenskyy did not refer to the blast in a video address on Saturday, saying merely that the weather in Crimea was cloudy.
“But however cloudy it is, Ukrainians know … our future is sunny,” he added. “This is a future without occupiers, across our territory, particularly in Crimea.”
The head of Ukraine's National Security and Defence Council posted a video of the bridge on social media alongside a video of Marilyn Monroe singing Happy Birthday, Mr President.
Since the war started on February 24, Ukrainian officials have regularly suggested they wanted to destroy the bridge. Ukraine's postal service said it would print a special stamp.
“Undoubtedly, we are witnessing the beginning of large-scale negative processes in Russia,” Mr Zelenskyy's adviser Mykhailo Podolyak said, blaming infighting among Mr Putin's circle as he attributed the blast to Russian operators.
Russian Foreign Ministry spokeswoman Maria Zakharova said Kyiv's reaction to the destruction of civilian infrastructure “testifies to its terrorist nature”.
The Russian National Anti-Terrorism Committee said a freight lorry blew up on the bridge's road at 6.07am local time (3.07am GMT). It said two spans of road bridge had partially collapsed, but that the arch spanning the channel through which ships travel between the Black Sea and Azov Sea was unharmed.
Emergencies Minister Alexander Kurenkov told state news agency TASS that quick-thinking railway workers who uncoupled the burning fuel wagons had kept the blaze from spreading.
Images showed half of the road blown away, with the other half still attached.
While the blast would “not affect army supply very much”, there would be problems with logistics for Crimea, Kirill Stremousov, the Russian-installed deputy administrator of the Kherson region, said in a social media post.