Iranian crude oil imports by Asia’s top four buyers dropped to the lowest volume in three years in 2018 amid U.S. sanctions on Tehran, but China and India stepped up imports in December after getting waivers from Washington. Asia’s top four buyers of Iranian crude — China, India, Japan and South Korea — imported a total 1.31 million barrels per day (bpd) in 2018, down 21 percent from the previous year, data from the countries showed. That was the lowest since about 1 million bpd in 2015, when a previous round of sanctions on Iran led to a sharp drop in Asian imports, Reuters data showed. The United States reimposed sanctions on Iran’s oil exports last November as it wants to negotiate a new nuclear deal with the country. U.S. officials have said they intend to reduce the Islamic Republic’s oil exports to zero. On a monthly basis, Asia’s imports …