US Secretary of State Hillary Clinton called on President Asif Ali Zardari on Friday and discussed the issues related to Pak-US cooperation in war against terrorism. President Zardari and Secretary Hillary Clinton in a one-on-one meeting that lasted for half-an-hour at the President House, discussed the issues of security, terrorism and extremism that were hampering the regional peace. Briefing the newsmen, Spokesperson to the President, Farhatullah Babar said a “candid, constructive and positive” exchange of views took place in the meeting that covered full spectrum of Pak-US relations. He said the issues of regional stability and security including countering terrorism and peace in Afghanistan were also discussed, according to a report of the Associated Press.