Diplomatic rapports with other Mediterranean countries, both Muslim and Christian, continued. Unlike earlier Hafsids, Uthman remained largely uninterested in the security of the beleaguered Emirate of Granada, although friendly contacts between the two continued. He also maintained ties with the Mamluks, a traditional friend, and established new ones with the Ottomans, sending a mission in 1454 to congratulate the sultan Mehmed II for his capture of Constantinople. Amicable relations with the Italian states and with Aragon continued, despite a thirteen-year break in relations between Piombino when Uthman was convinced by merchants from rival Italian states to embargo them. Uthman sent a lion as a gift to Francesco I Sforza, the Duke of Milan.