Florida teen Jack Sweeney shot to fame after his rather unusual hobby of tracking the private jet of Elon Musk came to the spotlight. The 19-year-old now has a new obsession.The Florida teenager has turned his sights on the yachts of Russian billionaires amid the Russian invasion of Ukraine.Sweeney, a freshman at the University of Central Florida, started tracking the aircraft of Russian oligarchs at the end of February. Now he’s following their yachts as the tycoons come under increasing sanctions pressure following Russia's invasion of Ukraine. Sweeney started tracking the private jets of Russia’s super-rich after receiving a number of requests. Using a list of planes being tracked by a blog called “Radar Spots,” Sweeney set up a Twitter account that has garnered over 390,000 followers in just days. Meanwhile, Italian police have seized villas and yachts worth 143 million euros ($156 million) from five high-profile Russians who were placed on sanctions lists following Moscow's attack on Ukraine.The luxury properties were sequestered in some of Italy's most prestigious retail estate locations - the island of Sardinia, by Lake Como and in Tuscany - while two superyachts were grabbed at their moorings in northern ports.The teen also monitored Russia's PutinSweeney had earlier published the movements of planes associated with Russian President Vladimir Putin.The 19-year-old had tweeted the live location of aircraft owned by Russian oligarchs, as well as the planes that are associated with Putin.He has made new Twitter bot accounts, namely @RUOligarchJets and @Putinjet, through which he frequently lets people know where the private aircraft of Russian billionaires and the President are.The Florida teen said he got requests to track Putin even before the war started, but as soon as Russia began attacking Ukraine, the number of requests from his online followers increased. The requests now also urged him to track the movements of private aircraft owned by Russian oligarchs and elites.