The Life and Death of the Kerch Bridge

by Donald Hill

2500 years ago the water in the Kerch Strait used to be four meters lower, but over time the islands in the strait were submerged. Tuzla island was formed during a 1925 storm with sediment from the Taman peninsula. During WW2, Germany started working on a bridge across the strait but retreated before they finished, leaving their building materials behind. The Soviets used that material to build a bridge from Chushka Spit to the Crimean Peninsula, which was the shortest distance across the strait. They finished it in 150 days in November 1944 and ice floes destroyed it 107 days later in February 1945.

The hastily constructed and short-lived Soviet bridge.

In September 2003, Russia started building a causeway from the Taman Peninsula to Tuzla Island, saying it was to prevent coastal erosion. In October 2003, Russia claimed the island was part of Russia. Ukraine said it would resort to arms if the construction crossed the Ukrainian border. Russia stopped construction at the border. In 2010, both countries agreed to build a bridge together. Russia invaded before that could happen.

Russian troops stationed in Crimea seized the peninsula in 2014. Russia began building the bridge in February 2016 and completed the vehicular bridge in April 2018 and the rail bridge in December 2019 at a cost of $3.7 billion.

(Bottom) The causeway stopped at the border. (Top) The vehicular bridge was built before the rail bridge, which has two tracks.

The Kerch Strait has a tectonic fault and the bedrock is covered by a 60 meter layer of silt. There are also 70 mud volcanoes in the strait that have eruptions of pressurized gases, heated water and fine sediments that are dangerous to constructions because they create unstable ground due to soil liquefaction and corrosive mudflows. The Kerch bridge has 7,000 piles that have been driven up to 90 meters beneath the water.

Even before construction was finished, there were warnings from Russians and others that the odds of it standing for any length of time was small. Several engineers said it was built with speed prioritized over durability and safety standards.

In 1927 there was a 6.7 magnitude earthquake off the coast of Yalta, and it destroyed 70% of the buildings in that city. Last week there were six quakes on 22 June, one with a magnitude of 4.5. There were more tremors on 24 June. These small tremors slowly weaken the bridge and the soil beneath the bridge.

Ukrainian Attacks

Ukraine tried to destroy the bridge three times. On 8 October 2022, a truck with 22,770 kilograms of explosives detonated, dropping three spans on one of the two vehicular bridge lanes and starting a fire in 7 of the 59-car train that was in an adjacent elevated rail bridge with two tracks. The fire likely weakened the rail bridge but Russian trains with passengers or light cargo loads ran on the unaffected track the next day. Passenger cars were able to use the adjacent vehicular lane that same day. The damaged lane was re-opened on 5 May 2023.

In the truck attack, three spans on one of the lanes were destroyed The supporting pillars remained intact. Fortunately, a train carrying fuel cars was adjacent when the explosions were detonated. The rail bridge remained functional but the heat weakened the pillars to an unknown degree, and the weight of the train cargos had to be reduced.

Two Sea Baby drones with 850 kg of explosives attacked the bridge on 17 July 2023. Two of the four lanes of the vehicular highway were knocked loose but remained on their supporting piers. One lane of traffic opened the next day. The bridge was fully reopened on 14 October 2023.

Two naval drones severely damaged one of the vehicular lanes, but the pillars remained intact.

Over several months, Ukraine planted 1,100 kg of explosives around the concrete piers and detonated them on 3 June 2025. The bridge was temporarily closed and reopened for traffic the same day.

Explosives placed under water at the base of the pillars (as opposed to the thinner vertical structures above water) did not significantly damage the pillars.

Future Attacks

Recently, Ukraine was able to attack the ports on both sides of the strait and any moving ships in between. If Ukraine chooses to attack the Kerch bridge again, destroying the pillar of the bridge would cause the most enduring damage. The pillars survived three previous attacks and they are a smaller target than the bridge spans. When the bridge spans were damaged, it took 3-7 months to repair them under non-combat conditions.

Given the freedom of movement for Ukraine’s naval and aerial drones, they would be able to attack any repair efforts and conduct further attacks on the bridge at will. An example of that is when the rail bridge at Rozdolne was attacked and Russia brought in repair equipment. The next night, Ukraine not only attacked the bridge and thoroughly destroyed the span, they destroyed some of the repair equipment, as well. Any damages to the Kerch bridge would probably not be repaired under these conditions.

Naval drones can be one method of attack. After two of the attacks on the bridge were conducted in the water on the shipping channel bridge, Russia built defenses consisting of a screen of barges, two rows of nets on the Black Sea side of the bridge, and one row of nets on the Sea of Azov side of the bridge. There is also a net that can be retracted so ships can pass through and then redeployed to block access. The channel is only 18 meters deep on the southern side, so it is difficult to avoid detection if the defenders are alert.

The causeway bridge doesn’t appear to have any defenses. If spans are damaged or destroyed at that location it will also stop traffic. In addition to the Sea Baby drones with an 850 kg warhead, there is an upgraded Sea Baby that has a 2,000 kg payload. Since 850 kg warheads were effective in an earlier attack, a 2,000 kg warhead should also be effective provided it arrives intact. Now that Russia knows naval drone attacks are a possibility, surprise would be harder to achieve.

Ukraine does have a Sea Baby submarine that it used to travel under the nets of Novorossiysk last December and attack a Russian submarine. It only had a 450 kg warhead, but the Marichka underwater drone that was used as a transport vehicle in the 2025 attack can carry 1,000 kg.

(Bottom) While Google Maps shows the defenses at the shipping channel bridge, it does not show any defenses around the causeway bridge.

Ukraine also has aerial drones and missiles. Options include the heavy-hitter Flamingo with its 1000 kg warhead but its navigation is spotty. Perhaps it could simply fly at the right elevation and hit the bridge anywhere at that altitude. Anywhere it hit would be severely damaged. There’s also the Long Neptune with a 260 kg warhead, and then there is the FP-2 and its 200 kg warhead that can be piloted directly into a pillar. That same pillar can be attacked repeatedly by different drones until it breaks.

(Top) The shipping channel. (Bottom) The Azov ports Russia uses to supply their army.

If Ukraine drops the span over the shipping channel that will block ships from using the Azov ports. This would not affect Ukraine because even if they liberate Beriansk and Mariupol at some point, they still won’t be able to use the strait until the war is over because Russia will control one side of it. In any case, if the shipping channel remains clear it is increasingly likely that Ukraine will attack ships using the Azov Sea either while sailing or in port.

On 22 June, when Ukraine was attacking the oil depot in Kerch, Russia lit smoke pots on the shipping channel span to theoretically disrupt missile and drone attacks. The defensive net in the water was also closed in case of a naval drone attack.

Russian Reaction

Russia moved an undisclosed number of air defense systems to protect the Kerch bridge. This is an attempt to keep the crossing intact and prevent the destruction of the memorial to imperial conquest.

For Ukraine, the military significance of the bridge has diminished since the rail to the rest of Crimea was severed at Vladislavovka. Because of the Black and Azov Seas, the Crimean peninsula has no depth to their air defenses, making them very vulnerable to drone attacks. Russia is reinforcing defeat, and placing more air defenses in a vulnerable position will lead to more losses of air defense components.

Ukrainian naval drones can carry FPV drones, as they have in the past, and attack anything within 20 km of the Black Sea coast, including air defense systems of the bridge. Aerial drones can carry FPV drones, as well, and it is almost impossible for air defense systems to shoot them down. Any target will do, but the radars would be a priority as their loss would reduce the chances of detecting Ukrainian missiles and drones. And then the larger drones would attack the missile systems themselves, which is how so many were destroyed over the years.

Ukraine has the ability to mass their attacks so that any one facility west of the Urals can be successfully damaged even if it was well defended. It is just a question of how many defense systems are in place and how many drones are shot down. It would benefit Ukraine to use the Kerch bridge as a black hole for Russian air defense systems and continue to destroy them with a favorable attrition ratio so long-ranged attacks elsewhere will suffer lower attrition rates.

Russia is fighting a war they are losing. They are losing control of Crimea with or without the Kerch bridge. Fighting a battle to keep the Kerch bridge is a battle that favors Ukraine and will increase the rate of Russian air defense losses. This is a battle that will help defeat Russia more quickly.

Whether the bridge stands or falls is increasingly the choice of Ukraine. Ukraine has the initiative in the air over Russia and the occupied territories, and Russia’s ability to defend itself is slowly diminishing.