An example laser tool configured for downhole laser beam generation is operable within a wellbore. The laser tool includes a generator to generate a laser beam. The generator is configured to fit within the wellbore, to withstand at least some environmental conditions within the wellbore, and to generate the laser beam from within the wellbore. The laser beam has an optical power of at least one kilowatt (1 kW). A control system is configured to control movement of at least part of the laser tool to cause the laser beam to move within the wellbore.