Hackers defaced the website of Bulgaria’s Orthodox Church on Thursday, accusing the organization of failing to condemn an attack on a mosque and underlining simmering sectarian tensions in the EU’s poorest country. An online group calling itself Milli Gucler (‘national forces’ in Turkish) briefly replaced the website’s homepage with a Turkish flag and a message saying the minority Muslim population would be defended. Many Bulgarian Muslims have roots in neighboring Turkey. Most Bulgarians are Orthodox Christians while Muslims make up about 12 percent of the population, according to surveys.