Sau­di Ara­bia, ruled by Sun­nis, is the world's largest oil ex­porter and pro­duces about 8.4 mil­lion bar­rels per day, enough to sat­is­fy about 8 per cent of world de­mand. The Saud­is have sent troops to Bahrain as part of a multi­na­tion­al force de­fend­ing the monar­chy there. That move was sharply crit­i­cised by Iran's Shi'ite lead­er­ship, which re­called its am­bas­sador to Sau­di Ara­bia. He­li­ma Croft, an an­a­lyst with Bar­clays Cap­i­tal, said Bahrain could be­come the new "cen­tral front" in an on­go­ing pow­er strug­gle be­tween Sau­di Ara­bia and Iran. The vi­o­lence al­so could hurt the Sau­di's diplo­mat­ic re­la­tion­ship with the US That would send shock­waves through oil mar­kets, Croft said. (AP)