Islamabad:  Former president Asif Ali Zardari has asked the US to "trust" and "mend ties" with Pakistan to defeat terrorism, amid tension between the two countries over an American drone strike that killed the Afghan Taliban chief in Baluchistan. Mr Zardari, who served as president from 2008 to 2013, also challenged those US Congressmen who doubt the intention of Pakistan and its role and commitment to take action against the dreaded Haqqani network, which is blamed for a number of attacks against American interests in Afghanistan. "I would challenge any faction in Congress that holds this view to come to Pakistan and bear witness to our solidarity and resolve," Mr Zardari wrote in an article in Chicago Tribune. He said in order to defeat terrorism the US and Pakistan should raise the trust level and mend ties. "Doubters should know that Pakistan has lost nearly 5,000 troops and many thousands of civilians in this fight. These losses were sustained in offensives against terrorist networks in the Federally Administered Tribal Areas - a long-time US priority," The Nation quoted him as saying in the article. The Pakistan People's Party leader also criticised the US for blocking the sale of eight F-16 jets to Pakistan and said the decision will be counter-productive and self-defeating. The US Congress has blocked funding for the jets citing Pakistan's unsatisfactory actions against the Haqqani network. Mr Zardari said the US must play its role along with Pakistan to combat terrorism. "Pakistan is ready and willing to continue its role at the front lines of the war against terrorism. But the US has a part to play in assuring our ability to fight and win on the battlefield." His comments came amid tension between Pakistan and the US following the May 21 drone strike that killed Mullah Akhtar Mansour deep inside Pakistan. Prime Minister's Adviser on Foreign Affairs Sartaj Aziz yesterday told a high-level US delegation in Islamabad that the drone attack "was not only a violation of Pakistan's sovereignty and breach of the principles of the United Nation's Charter, but has also vitiated bilateral ties". Pakistan-US ties are sliding down due to differences over handling of peace process in Afghanistan and US' growing defence ties with India, especially its support to India's membership for the elite Nuclear Suppliers Group (NSG). Mr Zardari said as the talks between the delegation and the Pakistani government continue, the US should reaffirm sale of fighter aircraft and with it faith in an indispensable partnership in defence of civilisation. He said the war against terrorism has not only cost Pakistan human lives but has also taken the country towards economic crisis. "Three decades of war has also meant slower economic growth and foreign direct investment than that of other developing countries whose borders are not active war zones. These are among the hidden opportunity costs of our commitment to fighting terrorism," he wrote.