A volatile buildup of weapons and resentment along the northern Somali coast culminated in the hijack of an oil freighter this week, the first such seizure by Somali pirates since 2012, experts and locals told Reuters on Wednesday. Gunmen hijacked the Aris 13, a small oil tanker, on Monday and are demanding a ransom to release the ship and its eight Sri Lankan crew, the EU Naval Force that patrols the waters off Somalia said. Now shipping companies are scrambling to find out whether the attack is a one-off, or whether pirates could once again threaten one of the world's...