For almost two decades since the 9/11 terrorist attacks, the paramount mission of the U.S. security establishment has been counterterrorism—specifically, defeating the jihadi terrorist enterprise and preventing it or any terrorist organization from mounting another devastating attack on the U.S. homeland. U.S. armed forces have played a major role in this national effort and have borne much of the human cost.
In the view of many senior military officials as well as civilian critics, however, pursuit of the war on al-Qa`ida and later the Islamic State, along with their affiliates, allies, and spin-offs, has commanded too much attention and has consumed too large a share of national defense resources for far too long. As a result, the ability to perform other critical military missions and responsibilities has been compromised.
And although the operational capabilities of al-Qa`ida have been degraded, the territory seized by the Islamic State has been recaptured, and there have been no further large-scale terrorist attacks anywhere near the magnitude of 9/11, the cost in blood and treasure has been high and the results are seen by many as disappointing. The war in Afghanistan, America’s longest war, seems unlikely to end in anything resembling a traditional military victory—or even end at all. Meanwhile, circumstances have changed. New threats have emerged, causing many to argue that U.S. armed forces need to change their priorities accordingly.
The 2018 National Defense Strategy (NDS) summary describes a complex array of threats and challenges to U.S. national security. These include the reemergence of long-term, strategic competition as the United States is only just awakening from a period of strategic atrophy. The NDS also points to a weakening post-WWII international order and increased global disorder. It mentions new challenges to U.S. military dominance as the United States’ competitive military advantage has eroded, rapid technological advancements, and the changing character of war. Its catalogue of threats includes rogue regimes with weapons of mass destruction; non-state actors including terrorists, transnational criminal organizations, cyber hackers, and others with increasingly sophisticated capabilities. Finally, it notes a U.S. homeland that is no longer a sanctuary from foreign attack.1 Some of these concerns come from assertions that could be challenged, but the appearance of new and complex challenges over the past 20 years is undeniable.