The Kerch Bridge explosion could have been caused by a US-supplied drone, say independent military researches.
According to reports the researches from Molfar examined the blast that caused the bridge to collapse on Saturday.
A vital transport link for Putin's army, the Kerch Bridge connected Crimea and Russia, leading to the Kremlin pointing the finger of blame at Ukraine.
The Kremlin said that a truck full of explosives blew up the passageway, however experts have disputed these claims.
After assessing the incident, the Molfar experts produced a report which was said to have demonstrated a lack of damage to the surface of the road, which would be indicative of a potential truck bomb.
Instead, researchers spotted something on a recording of the blast, which appears to show the explosion occurring underneath the bridge, reports the Daily Mail.
Russian spy agency, the FSB have reported that the bomb was shipped from Odesa via Bulgaria and Armenia to Georgia, where it crossed the border into Russia. Intelligence remarked that the bomb had taken two months to reach Russia, and that it had been disguised as industrial plastic sheeting.
They also claimed that paperwork for the disguised bomb had been changed at least twice during its journey.
Reportedly, the findings of the Molfar investigation said: "Theoretically, the bridge could be blown up from below. After all, at the time of the detonation, there was a wave under the section that collapsed, while there was [none] under the others.
"This may be the result of the operation of an air or water drone."
The experts had analysed footage from a camera that was attached to the railway. The recording showed a white object that looked to move in the water under the bridge before the explosion occurred.
The analysts reportedly said: "It's hard to tell if it's a wave or maybe a boat because in the first seconds after the explosion the camera was blinded.
"A water drone for special operations was already found near the coast of Sevastopol. It was probably delivered to our Armed Forces from the USA in April."
They also reportedly suggested that it could have been a Ukrainian-made drone.
In response, the Kremlin has arrested eight people over the bombing, including five Russians and "three Ukrainian and Armenian citizens".
Reportedly, the FSB described the explosion as a terrorist attack orchestrated by Kyrylo Budanov, the head of the Main Intelligence Directorate of the Ministry of Defense of Ukraine.
The FSB claimed that an employee of the Ukranian military intelligence had controlled the movement of the cargo throughout the entirety of its journey to the bridge.
The bridge was a personal project for Putin, which during the war in Ukraine, had become logistically vital to his military campaign. Down this route, supplies were sent to Russian troops fighting in south Ukraine.
The blast destroyed several fuel tankers on a train heading towards the annexed Crimean peninsula.
The state-owned Russian news service, RIA Novosti, said that a source had revealed the driver of the truck that was caught in the blast was not under suspicion.
The agency also reported that the cargo, thought to be a bomb, had been scanned at a customs post, where agents found nothing suspicious.
