This timeline examines the events that precipitated the U.S. war in Afghanistan as well as the history of the war.

Annual reports from the Department of State with regional overviews and topical chapters on terrorist organizations, etc.

President Obama's counterterrorism speech made strides toward greater transparency but missed opportunities to articulate a vision for moving beyond a perpetual war footing, says CFR's John Bellinger.

President Obama signed this directive on May 23, 2013, which he said in a speech at the National Defense University is a framework that governs the use of force by United States against terrorists.

President Barack Obama outlined on May 23, 2013, at the National Defense University, his administration's counterterrorism strategy, which include three areas: "targeted action against terrorists; effective partnerships; and diplomatic engagement and assistance." He discussed legal and moral concerns, and congressional oversight regarding the use of lethal targeted drone attacks and terrorist detention centers, and signed a policy directive to guide future operations.

Attorney General Eric Holder sent this letter on May 22, 2013, to U.S. Senate Judiciary Committee, addressing accountability, transparency, and legality of U.S. counterterrorism operations. He discloses previously classified information regarding the deaths of four U.S. citizens involved in terrorist groups, who were "outside the area of active hostilities" and were targeted by lethal drone attacks. This letter came before President Obama's speech at the National Defense University and his Presidential Policy Directive, which outline the administration's policies regarding counterterrorism operations, including drones and terrorist detention camps. See also the Department of Justice Memo: Lawfulness of a Lethal Operation Directed Against a U.S. Citizen who is a Senior Operational Leader of Al Qa'ida or An Associated Force.

A state of emergency in Nigeria's northeast signals that Islamist violence and the government's brutal response have rendered the region ungovernable, says CFR's John Campbell.

Elliott Abrams discusses the latest House hearing on the Benghazi embassy attack of September 11, 2012.

Stewart Patrick and Alexandra Kerr make recommendations to improve the counterterrorism efforts of the United States and its allies, in conjunction with CFR's Global Governance Report Card, published by the International Institutions and Global Governance program.

The article also provides a detailed case study of Hossam Yaacoub—the convicted Hizb Allah operative now serving time in a Cypriot prison for his role in a plot targeting Israeli tourists—to show how Hizb Allah has resurrected its terrorist capabilities. Drawn from the police depositions of interviews with Yaacoub after his arrest, the case provides unique insights into how Hizb Allah recruits and trains new operatives.

The Boston Marathon bombings illustrate the stresses on domestic intelligence gathering and counterterrorism in a democratic system, says CFR's Richard Falkenrath.

Julia Sweig reflects on implications of the Boston Marathon bombings in the midst of debates on gun control and immigration reform.

Micah Zenko reflects on the purpose and implications of investigating motivations behind terrorist attacks.

According to Ed Husain, "the answers to countering the appeal of radicalism among some Muslims in the West rests in more, not less, debating of religion, pluralist politics and integrating immigrants."

Ed Husain writes, "Boston will not be the last homegrown terror attack. Bombastic statements and burying our heads in the sand do not prepare us for future attacks."

U.S.-EU cooperation against terrorism has led to a new dynamic in U.S.-EU relations by fostering dialogue on law enforcement and homeland security issues previously reserved for bilateral discussions. Nevertheless, some challenges persist in fostering closer U.S.-EU cooperation in these fields. Among the most prominent are data privacy and data protection concerns.

The FBI released several documents and updates on their investigations on the Boston Marathon bombings, including a 2011 request from a foreign government on information about Tamerlan Tsarnaev.

In light of the terrorist attack at the 2013 Boston Marathon, Max Boot writes, "Keep calm and carry on."

Gayle Tzemach Lemmon reflects on the terrorist bombing at the Boston Marathon.