US President Barack Obama on Saturday mourned the deaths of 31 US Special Operations troops in a NATO helicopter crash in Afghanistan early today. "It''s a reminder of the "extraordinary sacrifices" being made by America''s military and its families," said Obama and regretted the killing of Afghan soldiers "who died alongside our troops in pursuit of a more peaceful and hopeful future in this country" . He further stressed that his country is determined to continue to work on deployment of security in Afghanistan. Earlier today the Taliban claimed responsibility for shooting down the helicopter. A NATO spokesman declined to comment on whether the helicopter had landed in the hands of Taliban militants or not.