United States of America remains one of the first countries to have established diplomatic ties with Pakistan. The relationship of both states dates back to Oct 20, 1947 which was based on economy and military assistance. During the 1950s the official visit of Pakistani Prime Minister Liaqat Ali Khan towards United States gradually improves their bilateral relationship and he stress upon Fundamental Human Rights and Equality of Opportunity. Pakistan signed Mutual Defense Agreement with United States and successively became member of SEATO and CENTO. Pakistan holds strategic importance not only in South Asia but also on International arena. After the 9/11 attacks and United States invasion in various countries to eradicate and destroy terrorist hubs brings both states in to same platform. Pakistan becomes one of the most important ally of United States in his ongoing campaign to destroy Taliban and Al-Qaeda Network. The purpose of this qualitative research is to analyze the Pak-US relations after the incident of terrorist attack on World Trade Centre that directs United States towards Pakistan and launched war on terrorism in Afghanistan for the maintenance of world peace.