Pakistan, the world's second most populous Muslim country (and sixth most populous overall), is strategically placed bordering India, Afghanistan, Iran, and China. Pakistan was originally a part of British India and split when India gained its independence in 1947. Pakistan lost another part of its lands when Bangladesh gained its autonomy after the 1971 war.
Effect of September 11th:
Before 9/11, the relationship was driven by American attempts to enable a democratic transition in Pakistan. The relationship changed drastically after the September 11th attacks on the United States. Realizing the need for supporters in the region, the Bush administration enlisted Pakistan as an ally in the "war on terror." The long border between Afghanistan and Pakistan, coupled with the tribal connections between both countries made Pakistan's collaboration a must for the United States to succeed in its counterterrorism efforts.
Pakistan also has an internal problem with Islamic extremism, a legacy of what has been called "Islamization" under former President Muhammad Zia-ul-Haq as well as money and support that was funneled by the United States and Saudi Arabia to support religious fighters against the 1979 Soviet invasion of Afghanistan. The United States and Pakistan cooperate on counterterrorism efforts with the Pakistani Army conducting raids on suspected terrorist in the peripheral, tribally controlled regions of Pakistan.
A Nuclear Power:
In May of 1998 Pakistan followed India by conducting its own nuclear test which signaled to the world the emergence of the first Muslim nuclear power and created the still standing nuclear standoff between India and Pakistan. Initially the tests triggered sanctions on both countries. The United States has since viewed the issue from a non-proliferation standpoint, with hopes of reducing nuclear arms in both countries, but a proposed nuclear deal with India has signaled a departure from that neutrality, at least in Pakistani eyes.
Tensions heightened between the United States and Pakistan when it was discovered thatDr. Abdul Qadeer Khan, a top Pakistani scientist, had transferred nuclear weapons technology to North Korea. In response to pressure, Khan was dismissed in March of 2001 from his position as chairman of Pakistan's national center for nuclear technology and material science, ironically named "Dr. A. Q. Khan Research Laboratories."
President Pervez Musharaf's hold on power in Pakistan has become increasingly tenuous, and he has come under increasing criticism from various elements of the U.S. policy and civil society communities for his suppressive domestic politics. In 2007, former Pakistani Prime Ministers Benazir Bhutto and Nawaz Sharif returned to Pakistan with the intention of participating in parliamentary elections. Bhutto was then assassinated on December 27, 2007.