The Iranian regime fired 16 ballistic missiles into Iraq on Jan. 8 at bases housing American troops. With no ballistic missile interceptors in range, U.S. forces could only watch and wait for impact. While no American or coalition partners were killed in the attack, next time could be different.

Iran launched its missiles from three sites in Iran, with 11 striking a base in Ain al-Asad and one hitting a base in Erbil. The lack of casualties should not lull planners into a false sense of security. A closer look at the attack demonstrates the need for additional ballistic missile intercept capacity.

Why did Tehran pick these targets? Since Qassem Soleimani was killed in Iraq, the idea of striking U.S. forces in Iraq was almost certainly appealing to Iranian leaders. Additionally, for domestic consumption, Iran’s leadership wanted to present dramatic images of the Iranian military launching a barrage of ballistic missiles toward U.S. troops.

But Iran may have chosen Ain al-Asad and Erbil specifically because the bases lacked ballistic missiles defenses. Images of American defenses destroying the incoming Iranian missiles would have severely undercut Tehran’s political objectives for the attack.

By creating a risk of interception, American missile defenses not only protect American lives, they complicate adversary military planning by injecting additional operational constraints, unknown variables and political risk. In short, robust U.S. missile defenses directly undermine our adversaries’ investments in missiles.

Yet, while the U.S. has defense systems capable of protecting the bases at Ain al-Asad and Erbil, the bases remained vulnerable because the U.S. lacks sufficient ballistic missile defense intercept capacity.

The U.S. possessed advance knowledge of the launches, tracked the missiles once airborne and provided its troops with early warning of their impending impact. But there were no interception options once the missiles were launched.

The Pentagon had deployed its finite inventory of Middle East-deployed, high-demand Patriot missile batteries elsewhere in the region to bases that the Pentagon deemed a higher priority. This has included, for example, bases in Saudi Arabia, Kuwait, Bahrain, Qatar and the United Arab Emirates.

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This decision, however, left roughly 5,000 U.S. troops in Iraq within striking distance of Iran without sufficient ballistic missile defenses.

Some might argue that the lack of casualties in the Iran strike demonstrates that such protection is not necessary. It would, however, be ill-advised and dangerous to assume a future Iranian missile attack against forward deployed U.S. troops would fail to inflict serious American casualties.

Following the attack, there has been widespread speculation about Tehran’s intentions. The debate has centered on whether Iran merely sought a face-saving but casualty-free assault that it could highlight for domestic consumption, or whether it was actually seeking to kill Americans, as the chairman of the Joint Chiefs of Staff, Gen. Mark Milley, indicated.

In crises and military conflicts, an adversary’s intentions can change quickly; it is therefore at least as important to focus on enemy capabilities.

Given the size of Iran’s ballistic missile arsenal, Wednesday’s attack was relatively modest in scale. As a 2019 Defense Intelligence Agency report assessed, Iran’s missile capabilities are formidable.

“Iran has the largest missile force in the Middle East, with a substantial inventory of close-range ballistic missiles (CRBMs), short-range ballistic missiles (SRBMs), and medium-range ballistic missiles (MRBMs) that can strike targets throughout the region as far as 2,000 kilometers from Iran’s borders,” the report noted.

In addition, the DIA reported that Iran is working to increase the accuracy of its missile arsenal.

It is worth remembering the precision and sophistication of Tehran’s attack against Saudi oil facilities last September, which combined drones and cruise missiles to deliver a pinpoint attack and temporarily knocked out half of Saudi Arabia’s oil production capacity.

While Tehran reportedly did not employ drones and cruise missiles in the Jan. 8 attack, there is little to preclude Tehran from using such weapons and tactics in the future. A barrage of a hundred or more ballistic and cruise missiles, as well as drones, targeting major U.S. bases throughout the region could incur a deadly result.

In a future crisis, insufficient missile defense could force Washington to conduct a risky preemptive strike, or in the case of American casualties, a retribution strike. Either scenario is escalatory and avoidable.

The U.S. Army has wisely made air and missile defense one of its top six modernization priorities. Ensuring U.S. soldiers have next-generation capabilities is important, but commanders must also have those capabilities in sufficient quantity.

The Jan. 8 attack should demonstrate for Americans the value of missile defense and the fact that the U.S. currently does not have enough.