A US-provided Abrams tank during a training exercise in Poland, on April 12, 2023.Artur Widak/Getty ImagesUkraine has removed Abrams tanks from the front lines, Pentagon officials told the Associated Press.They said the tanks are struggling with Russia's drones and attack tactics.Drones proliferating over Ukraine's skies have proved fatal to high-value targets, including tanks.Ukraine has withdrawn its US-supplied Abrams tanks from the front lines in the face of Russian drone warfare tactics, two US defense officials told the Associated Press.One of the officials, who spoke on condition of anonymity, said swarms of drones flying over Ukraine meant "there isn't open ground that you can just drive across without fear of detection."Christopher Grady, the vice chairman of the Joint Chiefs of Staff, confirmed the decision to move the tanks away from the front."When you think about the way the fight has evolved, massed armor in an environment where unmanned aerial systems are ubiquitous can be at risk," Grady told the AP.The US agreed to send 31 M1A1 Abrams to Ukraine in January last year, after months of Ukraine asking for advanced weaponry to help counter Russia's invasion.Ukraine received the first batch of the tanks in September.But it doesn't look like things have gone to plan.A Russian reconnaissance drone knocked out an M1 Abrams tank near Avdiivka in eastern Ukraine in February, according to Russian state media.Ukraine has lost five Abrams tanks in recent months, The New York Times reported this month, citing an unnamed senior US official.