The forces of Bashar al-Assad, the Syrian president, are expanding their use of widely banned cluster bombs, causing “mounting civilian casualties,” an international human rights group said. Saturday’s report by Human Rights Watch comes just after the conflict reached the two-year mark earlier this week. The New York-based group said Syrian government forces have dropped at least 156 cluster bombs in 119 locations across the country in the past six months, causing mounting civilian casualties. “Syria is expanding its relentless use of cluster munitions, a banned weapon, and civilians are paying the price with their lives and limbs,” said Steve Goose, HRW director of the arms division. “The initial toll is only the beginning because cluster munitions often leave unexploded bomblets that kill and maim long afterward,” Goose said. “All nations that have joined the treaty banning cluster bombs have a legal obligation to speak out and condemn Syria’s ever-expanding use of these indiscriminate weapons, yet too few are doing so,” he added.