Al-Shabaab has never conducted a successful attack in the West and has not conducted a mass-casualty attack outside of Somalia since it carried out bombings in Kampala, Uganda, in 2010.
-- Islamist militant groups remain a threat to stability in Libya in the post-Moammar Gadhafi era. Ansar al-Sharia's loose network of Islamist militants have conducted attacks and gained some legitimacy among the local populace in Benghazi. Ansar al-Sharia is not, however, organizationally or operationally linked to al Qaeda, and it operates only within Libya.
-- The Pakistani Taliban, also known as Tehrik-i-Taliban Pakistan, is largely a threat to Pakistan, Afghanistan, NATO soldiers and Western interests in the Afghanistan-Pakistan region. It has attempted only two attacks outside the region. TTP has not conducted an attack on American soil since it directed Faisal Shahzad to carry out a car bombing that proved unsuccessful on May 1, 2010, in Times Square.
-- The Afghan Taliban continue to lead a potent insurgency in Afghanistan, launching persistent attacks against U.S. forces, as well as military, diplomatic, and aid facilities. They remain in control of significant swaths of land in rural Afghanistan, and will continue to threaten Afghan stability after the NATO combat mission ends in December 2014. However, they have shown no interest in mounting an attack against the U.S. homeland.
-- The Pakistan-based Lashkar-e-Taiba has not conducted a mass-casualty attack outside of the Afghanistan-Pakistan region since its lethal rampage in Mumbai in 2008. Similarly, the Islamic Movement of Uzbekistan and the Islamic Jihad Union have not showed an interest in or ability to engage in international terrorism since an IJU-linked terrorism cell was broken up in Sauerland, Germany, in 2007.
-- Because of continued government crackdowns throughout Southeast Asia, the once-virulent threat posed by the al Qaeda aligned regional terrorist group Jemaah Islamiyah has decreased significantly over the past few years.
Terror groups have local preoccupations
Given the weaknesses and the local preoccupations of the terrorist groups described in this story, many U.S. counterterrorism officials believe the chances of a large-scale, catastrophic terrorist attack in the United States by al Qaeda or an al Qaeda-affiliated or inspired organization are quite small.
Also, the long-term prognosis for most of these terrorist groups is poor because they have all tended to kill many Muslim civilians, and they offer no political or economic ideas to cure the real problems of much of the Islamic world.
However, continued unrest throughout the greater Middle East, especially the current turmoil in Egypt, the rising tensions across the region between Sunnis and Shia, the continuing Syrian civil war and the uncertain future of Afghanistan after U.S. and NATO combat troops are withdrawn in December 2014 are all potential wild cards that could create an environment that gives al Qaeda and allied groups opportunities to resuscitate themselves.
And at home, the Boston Marathon bombings remind us that the United States still faces a threat from disaffected individuals inspired by al Qaeda's ideology and who often radicalize in the online world.
Although they are difficult to detect, these individuals are also quite unlikely to be capable of perpetrating an attack even remotely on the scale of 9/11.
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