How Effective Are the Post-9/11 U.S. Counterterrorism Policies Within and Outside the United States?

• Published date: 01 December 2024
• DOI: http://doi.org/10.1177/08874034241271175
• Author: Ahmet Guler,Mustafa Demir
• Date: 01 December 2024

https://doi.org/10.1177/08874034241271175

Criminal Justice Policy Review

2024, Vol. 35(5-6) 243 –272

© The Author(s) 2024

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DOI: 10.1177/08874034241271175

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Article

How Effective Are

the Post-9/11 U.S.

Counterterrorism Policies

Within and Outside

the United States?

Ahmet Guler1 and Mustafa Demir2

Abstract

This study examined the effectiveness of post-9/11 U.S. counterterrorism policies

in preventing terror attacks and reducing casualties against American targets within

and outside the United States. Monthly data on terrorism incidents from July

1981 through December 2020 were obtained from the Global Terrorism Database

(N= 462). The results of monthly interrupted time-series analyses showed that

within the United States, after the 9/11 attacks, the number of attacks, the number

of successful attacks, and the successful attack rate statistically significantly

decreased in the first month following 9/11; then, no significant increase was

observed in the trend of those outcomes. Outside the United States, after the 9/11

attacks, the trend of the number of successful attacks, the number of victims, the

number of nonfatal victims, and the victim rate statistically significantly decreased.

The results suggest that post-9/11 U.S. counterterrorism policies are effective

both domestically and internationally. These findings and their policy implications

are discussed.

Keywords

9/11 attacks, U.S. counterterrorism policy, terror attacks, counterterrorism

1The Pennsylvania State University, University Park, USA

2City University of New York, New York City, USA

Corresponding Author:

Ahmet Guler, Department of Sociology and Criminology, Pennsylvania State University, 1003 Oswald

Tower, University Park, PA 16802, USA.

Email: aguler@psu.edu

1271175CJPXXX10.1177/08874034241271175Criminal Justice Policy Review XX(X)Guler and Demir

research-article2024

244Criminal Justice Policy Review 35(5-6)

Introduction

On September 11, 2001, Al-Qaeda-affiliated terrorists committed suicide attacks using

hijacked planes against prominent targets in the United States. These unexpected and

brutal attacks killed nearly 3,000 innocent individuals and injured nearly 6,000 people

(Kean & Hamilton, 2004). The 9/11 terrorist attacks, defined as a “watershed moment”

in the history of transnational terrorism, prompted major changes in the realm of U.S.

counterterrorism policy (Enders & Sandler, 2005; Grennan & Toros, 2021; Oliver,

2009; Sandler, 2003).

The U.S. government has employed several counterterrorism strategies to combat

international terrorism, ranging from hard power to soft power strategies such as

diplomacy, international cooperation, international conventions, economic induce-

ments, economic sanctions, law enforcement cooperation, extradition, covert action,

and military force (Nye, 2009). From the 1970s to the 1990s, the U.S. government’s

efforts to fight against terrorism could be framed as an antiterrorism policy that

mainly focused on defensive measures to reduce the vulnerabilities of the U.S. citi-

zens and properties to terrorist attacks. However, this policy shifted to a counterter-

rorism approach after the 9/11 terrorist attacks, aiming to provide better means and

ways to take more offensive measures in preventing, deterring, and responding to

terrorism. In this respect, several federal agencies and departments have specifically

undertaken active roles in efforts toward minimizing the risks of domestic and for-

eign terrorist threats (Rasmussen, 2016). However, these counterterrorism efforts

have received criticism, and their effectiveness has been questioned by some scholars

and counterterrorism experts (Crenshaw, 2010; English, 2019; Perl, 2005; Stewart &

Mueller, 2008).

Although the 9/11 terrorist attacks increased a general interest in the studies of ter-

rorism and in applying empirical research toward policy-making (Silke, 2006), more

quantitative studies are still needed to examine the effectiveness of the U.S. post-9/11

counterterrorism policies (Phillips, 2023). While some researchers have studied the

effects of 9/11 terrorist attacks on several aspects of global terrorism (Davies, 2018;

Demir & Guler, 2023; Enders & Sandler, 2006; Santifort-Jordan & Sandler, 2014; M.

Smith & Zeigler, 2017), more empirical research is needed to assess the impact of

counterterrorism policy changes after 9/11 specifically on the success of countering

terrorist attacks within and outside the United States. These empirical research efforts

can help evaluate the effectiveness of counterterrorism efforts and develop optimally

effective evidence-based counterterrorism policies (Lum & Kennedy, 2012).

Literature Review

The U.S. Counterterrorism Policy

Counterterrorism is a complex and multifaceted term that includes domestic and for-

eign policy efforts to limit the activities of terrorist organizations and their affiliates at

home and abroad.