The ships span the length of a football field or longer, come outfitted with helipads and swimming pools, and have shown up at ports around the world – towering over nearby fishing vessels and motorboats like giants. Yachts owned by Russian oligarchs – who have bought some of the largest and most extravagant “superyachts” on the planet – are gleaming symbols of how Russia’s elite have profited under the government of President Vladimir Putin. Now, as Russian forces ramp up their deadly military campaign in Ukraine, the yachts are emerging as key targets of the US and European allies, who are vowing to seize property owned by Putin’s enablers. Disputes are already erupting: French officials seized a yacht Wednesday night that they said was linked to Igor Sechin, a sanctioned Russian oil executive and close Putin associate, as it was preparing to flee a port. But the company that manages the ship denied Sechin was the owner. And the White House said German officials had seized another oligarch’s yacht in Hamburg, while local authorities denied any ships had been confiscated. The French seizure shows that confiscating oligarchs’ yachts will require a concerted global effort – and it’s likely to mean protracted legal battles around the world, experts said. A CNN review of maritime location data from the website MarineTraffic found that more than a dozen yachts that have been reported to be owned by Russian oligarchs are spread out across the world, from the crystal waters of Antigua to ports in Barcelona and Hamburg to atolls in the Maldives and Seychelles. In several cases, the billionaires’ yachts have been on the move in the days since the Russian offensive began. Meanwhile, officials around the world are also enforcing sanctions on a far less flashy but still important group of vessels: oil tankers and container ships the US Treasury Department says are owned by the subsidiary of a bank with close ties to Russia’s defense industry. French authorities intercepted one of the cargo ships last weekend, and a Malaysian port refused to let another dock. Sanctions and asset seizures “make it more difficult for the Kremlin to persuade capable people of getting involved in its activities and thereby weaken the grip of the Kremlin over elites,” said William Courtney, a former US ambassador and current executive director of the RAND Business Leaders Forum, whose members include Russian and Western leaders. President Joe Biden put the Russian elite on notice in his State of the Union speech Tuesday night. “To the Russian oligarchs and the corrupt leaders who bilked billions of dollars off this violent regime: No more,” Biden declared. “We are joining with European allies to find and seize their yachts, their luxury apartments, their private jets. We’re coming for your ill-begotten gains.” The US Department of Justice launched a new task force – dubbed KleptoCapture – to help put Biden’s words into action. The effort includes prosecutors, federal agents and experts in money laundering, tax enforcement and national security investigations from the FBI, the IRS, the US Marshals Service, and the US Postal Inspection Service, Attorney General Merrick Garland said in a statement Wednesday. “We will leave no stone unturned in our efforts to investigate, arrest, and prosecute those whose criminal acts enable the Russian government to continue this unjust war,” Garland said. Russian-tied yachts docked around the world Yacht ownership is extremely difficult to confirm, with the ships often registered to management companies or shell corporations in an apparent effort to disguise ownership, experts say. But more than a dozen of the billionaires included in a list of Russian “oligarchs” the Treasury Department released in 2018 have been tied to yachts in media reports in recent years, according to a CNN review. Most of the oligarchs who reportedly own yachts are not yet facing US sanctions. However, some have been sanctioned by the European Union or the United Kingdom, and could be added to US sanctions lists as well. Amber Vitale, a former official with the Treasury’s Office of Foreign Assets Control, which enforces sanctions, said that US sanctions generally only prevent Americans and American companies from interacting with sanctioned individuals. That means the oligarchs’ yachts could be safe from seizure if they stay in international waters or in countries that haven’t issued their own sanctions. “However, it would get very difficult to operate for long if many allied nations impose similar prohibitions,” Vitale said in an email. “Vessels need ports, fuel, operators/captains, repairs and supplies. Without access to these things they could be stuck floating at sea waiting for rescue or resolution.” The seizures have already begun, with French officials taking the Amore Vero, the yacht they said is owned by Sechin, according to a statement from France’s Ministry of Economy and Finance. The yacht arrived at the French port of La Ciotat on January 3 for repairs, but was “making arrangements to sail urgently, without having completed the planned work” when it was seized on Wednesday, the ministry said. Sechin, the CEO of the Russian oil company Rosneft, was sanctioned by the EU earlier this week, and Rosneft itself was sanctioned by the US in 2014. But a yacht management company associated with the ship denied Sechin owned it. “I can absolutely say that Igor Sechin is not the owner,” a spokesperson for Imperial Yachts, which manages the Amore Vero, told CNN. “The rightful owner is appealing the decision to seize the vessel.” Legal experts told CNN that oligarchs were likely to transfer assets such as yachts to friends or family who aren’t sanctioned to try to prevent them from being seized. Catherine Belton, the author of a book on Putin, said she expected oligarchs were “feverishly engineering deals where ownership changes could be triggered.” “It’s going to be a game of cat and mouse,” she said. The French ministry said that the Amore Vero, which has an onboard gym and beauty salon and won an award for yacht design, is owned by a company whose “main shareholder” is Sechin. Sechin served as Russia’s deputy prime minister in Putin’s cabinet before becoming CEO of Rosneft, one of the country’s largest companies, in 2012. The seizure may also scare other Russian oligarchs into getting their ships out of EU ports. The Dilbar, one of the largest yachts in the world, which is reportedly owned by Russian billionaire Alisher Usmanov, arrived in Hamburg, Germany in late October, according to MarineTraffic data. There was confusion about the ship’s status on Thursday: Usmanov was sanctioned by the EU earlier this week, and Forbes reported that German authorities had seized the 156-meter ship, which can carry up to 96 crew members and 24 guests. The US Treasury Department also sanctioned Usmanov on Thursday, specifically calling out the Dilbar as evidence of his “luxurious lifestyle.” But a spokesperson for the Hamburg economic authority told CNN Thursday that “no yacht has been seized by authorities or customs at the port in Hamburg at this moment in time.” German customs officials did not respond to CNN’s requests for comment, and the shipbuilding company that reportedly had been refitting the yacht declined to comment. The Luna, a yacht reportedly owned by Farkhad Akhmedov, an Azerbaijani billionaire who previously led a Russian natural gas company, was also in Hamburg as of the latest MarineTraffic data from earlier this week. Akhmedov, who has not been sanctioned, kept the nine-deck, 115-meter Luna after an acrimonious divorce that was the largest divorce case heard in Britain’s legal history. The yacht features missile detection technology and bulletproof windows. Several yachts reportedly owned by Russian oligarchs have been docked at a port in Barcelona, including the Solaris, which has been tied to Roman Abramovich, the billionaire who announced Wednesday that he would sell the Chelsea Football Club and donate proceeds to a foundation for people impacted by the invasion of Ukraine. Abramovich hasn’t been sanctioned. The Galactica Super Nova, reportedly owned by Russian oil company executive Vagit Alekperov, left Barcelona on Saturday and crossed the Mediterranean to Tivat, Montenegro, before sailing south into the Adriatic Sea. While Alekperov hasn’t been sanctioned, he is president of Lukoil, which has been hit by US sanctions in the past. Other Russian-linked yachts are in the Caribbean, including Eclipse, another yacht owned by Abramovich, which is among the world’s largest and includes a swimming pool that can be transformed into a dance floor, and the Anna, reportedly owned by oligarch Dmitry Rybolovlev, who once purchased a Florida mansion from former President Donald Trump. Rybolovlev hasn’t been sanctioned. Courtney, the former ambassador, said that he expected Russian oligarchs took most of their assets out of the US after two billionaires were sanctioned in 2018, and predicted that they would try to move their yachts out of Western European countries to avoid them being seized. “We are likely to see more of a redistribution geographically of some of those assets,” Courtney said, to countries “that are seen as less likely to sanction,” possibly in the Middle East. Several yachts connected to Russian oligarchs have arrived in recent weeks in the Maldives, an Indian Ocean archipelago nation. They include the Clio, reportedly owned by oligarch Oleg Deripaska, which left Sri Lanka in early February and has been sailing between various Maldives atolls since then, according to MarineTraffic. Deripaska was sanctioned by the US in 2018. None of the oligarchs mentioned in this story responded to requests for comment from CNN sent to their spokespeople, businesses or lawyers. Perhaps the clearest example of a yacht with supposed ties to the Russian elite fleeing the West is a Russian-flagged ship named Graceful. Speculative news articles in the German media have reported that the ship belongs to Putin himself, although there’s no concrete evidence that that’s the case. Graceful departed Hamburg in early February – roughly two weeks before the invasion of Ukraine – and sped to Kaliningrad, Russia, the MarineTraffic data shows. No location data has been recorded since it arrived in the Russian city on February 9. Hackers last week successfully altered maritime traffic data to make it appear that the yacht’s destination was “hell” and it had run aground on Snake Island in Ukraine – where Ukrainian soldiers’ profane response to a Russian warship went viral on social media. Sanctions will likely spark legal battles over the yachts, and require government officials to prove ownership, experts said. “A sanctioned person may say to the government that the asset you have frozen is not one of my assets,” arguing that it is registered in a family member’s name or a shell corporation that has not specifically been sanctioned, said Raj Bhala, a professor at the University of Kansas Law School and a sanctions expert. “The oligarch could argue before the government that you don’t really have the legal authority to seize my asset.” But there are new dangers for the oligarchs’ yachts beyond legal proceedings: A Ukrainian ship engineer was arrested in the Spanish island of Mallorca for trying to sink a yacht owned by a Russian military export company executive, local news outlets reported. “I don’t regret anything I’ve done and I would do it again,” the engineer declared in court on Sunday, according to the Majorca Daily Bulletin. “They were attacking innocents.” Sanctioned shipping vessels seized, blocked from ports Even as Biden and other officials have focused their public comments on oligarchs’ yachts, the US is also going after other shipping vessels with ties to Russia. Last week, the Biden administration announced sanctions against five oil, cargo and container ships that the Treasury Department says are owned by a subsidiary of Promsvyazbank, a Russian bank that has given billions of dollars to support Russian defense companies. The sanctions block any Americans from doing business with Promsvyazbank. French authorities seized one of the cargo ships, the Baltic Leader, on Saturday as it was headed from France to Saint Petersburg, Russia, “as part of an operation carried out in cooperation with US authorities,” according to France’s finance ministry. The ship is now anchored at a port in northern France, MarineTraffic data shows. A port operator in Malaysia declined the request of one of the other vessels, an oil tanker named Linda, to dock there on March 5 “in order not to violate any sanctions,” Malaysia’s Ministry of Transport told CNN. The decision was first reported by Reuters. Promsvyazbank did not respond to CNN’s request for comment, but has publicly denied that its subsidiary owned the Linda, and said it no longer owns the Baltic Leader. Two of the other US-sanctioned ships are now in the process of having their leases withdrawn from Promsvyazbank’s subsidiary, according to a statement from Russian company FESCO Transportation Group. Some of the ships have been accused in recent years of violating past US sanctions by transporting Iranian oil. A Turkish petroleum company had agreed to service another one of the ships – an oil tanker named Pegas – at one of its terminals earlier this year, but after receiving a report that the ship may have been carrying Iranian cargo, the transaction was canceled, according to a spokesperson for the company, Opet.