WASHINGTON: Russia’s claim that it killed Islamic State group spokesman and top strategist Abu Mohamed al-Adnani is a ‘joke’ as the strike was conducted by a US Predator drone, American officials said on Wednesday. “That’s a joke,” a US Defence official said when asked about Moscow’s Adnani claim, speaking on condition of anonymity to discuss military operations. “It would be funny if not for the character of the campaign the Russians have undertaken in Syria,” he said. Another US official – again speaking on condition of anonymity – said the strike was carried out by a Predator drone that fired a Hellfire missile at a car in which Adnani was believed to have been traveling.