The Kerch Bridge, the link between Russia and Crimea, suffers a powerful explosion

"Everything illegal must be destroyed," writes Mykhailo Podolyak, a Ukrainian presidential adviser, shortly after an explosion destroyed part of the famous Kerch Bridge, the link between Russia and the occupied Crimean peninsula.

A new blow for the Kremlin and its war against Ukraine. The 19-kilometre bridge, one of the main symbols of Russia's occupation of Crimea, represents one of the most important logistical supply routes for Russian troops on the peninsula and in southern regions of Ukraine.

"Everything that was stolen must be returned to Ukraine, everything that belongs to the Russian occupation must be expelled," Podolyak adds, warning that this is only the "beginning". With the cause of the explosion still unclear, a possible act of sabotage or a missile attack is being considered. AFP also reports that a car bomb may have triggered the explosion.

One expert tells the BBC that "the absence of damage to the road surface suggests that an air-dropped weapon was not used". It is therefore possible that this was "a well-planned attack from below". "I suspect that the explosives on the road and on the train deck were set off simultaneously," he adds.

The bridge - inaugurated in 2018 by Vladimir Putin himself - has been one of Ukraine's main targets since the start of the invasion. Last April, Oleksiy Danilov, secretary of Ukraine's National Defence and Security Council, did not rule out attacking the infrastructure. "If there is an opportunity, we will definitely do it," Danilov was quoted as saying by Ukrinform.

The attack comes a day after Putin's 70th birthday. The Russian president has ordered an emergency commission to be set up to deal with the incident. Moscow has claimed that the explosion was caused by a truck, according to RBK.

The speaker of the Crimean parliament, Vladimir Kontantinov, blamed the explosion on "Ukrainian hooligans". "They finally managed to reach the Crimean bridge with their bloody hands," he added. Kontantinov also said the damage would be repaired "immediately as it is not serious".

Several Russian politicians have already called for a firm response from Moscow. The explosion comes amid a major counteroffensive by Ukraine in which it has recaptured several key locations in the east of the country. "There is no doubt that Russia will give an adequate, conscious and possibly asymmetric response to the emergency on the Crimean bridge," a Russian senator told RIA Novosti.

The Russian media also quoted Duma deputy Oleg Morozov as saying that the attack on the Crimean bridge "is no longer just a challenge, it is a declaration of war".

The partial destruction of one of the main supply routes for Russian troops in Ukraine represents one of Kiev's latest major victories and one of the recent blows against the Kremlin. Ukrainian armed forces have liberated numerous key towns in the east of the country in recent weeks.

At the same time, fears of a possible nuclear attack by Russia are growing among the international community. Recently, US President Joe Biden warned that the world was facing "nuclear Armageddon". "Putin is not kidding," he said, alluding to the Russian president's multiple threats.