Prime Minister of Pakistan Muhammad Nawaz Sharif expressed deep concern over the continuing drone strikes by the United States in the country, said an official press release on Monday. While talking to US Secretary of Defence Chuck Hagel who called on him, the Pakistani premier stressed that drone strikes were counter-productive to the government's efforts to combat terrorism and extremism on an enduring basis. The US Defense Secretary held in-depth exchange on the whole range of issues of mutual interest between the two countries. According to a press release by Foreign Office, the two leaders agreed to work together to strengthen Pakistan-US relations and advance the shared interest of a stable, secure and prosperous Pakistan and the region. PM Nawaz stressed the importance Pakistan attached to a peaceful, stable and united Afghanistan and reaffirmed Pakistan's support for the Afghan peace and reconciliation process. The US Defense Secretary acknowledged Pakistan's efforts to support an inclusive reconciliation process in Afghanistan. The two leaders also reviewed the current state of bilateral defence and security cooperation and explored ways of further expanding cooperation in this important area of the relationship, the release added. This was the first visit by the US defense secretary in nearly four years as Hagel flew from Afghanistan to Pakistan to meet the premier and the country's new army chief General Raheel Sharif. According to a press release by media wing of Pakistan military, Inter Services Public Relations (ISPR), Chuck Hagel called on Chief of Army Staff (COAS), General Raheel Sharif at General Headquarters. Issues concerning defense relationship, Pak-US bilateral ties and regional stability came under discussion, the release added. The Ambassador of the US in Pakistan Richord G. Olson and US Acting Assistant Secretary of Defence Dr Peter Lavoy accompanied US Secretary of Defence.