RAWALPINDI: US special representative for Afghanistan and Pakistan Richard G Olson called on Chief of Army Staff General Raheel Sharif at General Headquarters on Monday, ISPR said in a brief statement. According to the statement, during the meeting overall regional security situation with particular reference to situation in Afghanistan was discussed. Olson appreciated results of the ongoing operation Zarb-e-Azb and the efforts of Pakistan in the fight against terrorism, the statement added.