A steering tool includes an internal tube disposed inside an external tube. The internal and external tubes are arranged for longitudinal axial movement relative to one another. A distal portion of the internal tube is fixedly joined to a distal portion of the external tube. At least one of the tubes may include, over at least some of its length, two continuous, longitudinal zones of solid material separated from each other by a longitudinal gap. At least one of the tubes may include a flexible distal portion distal to the joining zone, the flexible distal portion being more flexible than other portions of that tube.
