Colombian sappers on Tuesday effected the controlled detonation of a grenade planted along a route taken by President Alvaro Uribe, and authorities said they were trying to determine if it was part of an assassination attempt. The incident took place on a highway in the northern province of La Guajira. A police spokesman said an anonymous telephone call had tipped officials off to a hand grenade placed inside a barrel and set to be activated by remote control along the route between Riohacha, the provincial capital, and Maicao, a town near the Venezuelan border. Full Story