Videos of the damaged Crimean bridge have spread like wildfire on social media; this is already being compared to the sinking of the Russian warship Moskva in April."The guided missile cruiser Moskva and the Kerch bridge - two notorious symbols of Russian power in Ukrainian Crimea - have gone down," tweeted Ukraine's ministry of defence.Oleksii Danilov, Secretary of Ukraine's National Security Council, wasn't the only one noting that the attack came just a day after Vladimir Putin's 70th birthday, tweeting a video of the damaged bridge next to Marilyn Monroe's famous performance of Happy Birthday, Mr President from 1962.Coming on the back of weeks of mostly good news from the battlefront, where Ukrainian forces continue to take back territory seized by Russia back in February and March, the sight of the crippled, burning bridge is a massive additional boost to morale.Any number of theories are doing the rounds - from a Ukrainian special forces operation to the work of partisans in Crimea, a missile strike, or even a suicide bomb."