United States researchers announced a historic nuclear fusion breakthrough on Tuesday, hailing a "landmark achievement" in the quest for a source of unlimited, clean power and an end to reliance on fossil fuels.

• The Lawrence Livermore National Laboratory (LLNL) said it had used the world's largest laser to create, for the first time, a fusion reaction that replicated the process that powers the sun and generated more energy than it took to produce—a goal pursued by scientists for decades.
• Nuclear fusion has been touted by its supporters as a clean, abundant and safe source of energy that could eventually allow humanity to break its dependence on coal, crude oil, natural gas and other hydrocarbons driving a global climate crisis.