The United States can no longer afford to “react to threats after they have emerged,” argues Emily Estelle in a new report on the dangers posed by the violent strains of Salafism, the fundamentalist Islamic ideology espoused by Islamic State. Noting the growing power vacuum in the Middle East and the pressing challenges posed by Russia and China, Estelle outlines a path for the U.S. to “avert rather than mitigate [the] risk” of global Salafi-jihadist terror. Failure to do so, she contends, will exacerbate domestic tensions while accelerating wide-ranging threats to national security.

A new jihadist wave is the last thing Western policymakers want to recognize or prepare for. But Americans face a more serious terror threat than they realize. The global Salafi-jihadist movement, led by al-Qaeda and Islamic State, has not faded into irrelevancy but has grown greatly in manpower, wealth, capability, and geographical extent and is stronger by some measures than it has ever been.

The movement’s flashiest endeavors—spectacular terror attacks and a border-crossing caliphate—are in a lull that the largely temporary effects of counterterrorism pressure only partly explain. Deliberate adaptation is also at play; Salafi-jihadist leaders have learned to eschew direct attacks on the U.S. and European homelands, on the whole, to avoid drawing attention to their successes in putting down deep roots in many countries. But they have not given up their aim—toppling and replacing states across the Muslim world—or their willingness to use terror attacks to achieve their ends.

Over the past two decades, the U.S. government has disaggregated threats and sought to manage them sequentially: small or lone-wolf attacks in the United States; resurgent Salafi-jihadist groups across Africa, the Middle East, and South Asia; government collapse in these regions; and mass-migration refugee crises driven by conflict and climate change. These problems range from manageable to inconsequential in the establishment worldview. But this approach fails to recognize the cumulative weight of these interconnected developments and the major threat they represent in combination.

Early Friday morning, Israel attacked military installations near the Iranian cities of Isfahan and nearby Natanz, the latter being one of the hubs of the country’s nuclear program. Jerusalem is not taking credit for the attack, and none of the details are too certain, but it seems that the attack involved multiple drones, likely launched from within Iran, as well as one or more missiles fired from Syrian or Iraqi airspace. Strikes on Syrian radar systems shortly beforehand probably helped make the attack possible, and there were reportedly strikes on Iraq as well.

Iran itself is downplaying the attack, but the S-300 air-defense batteries in Isfahan appear to have been destroyed or damaged. This is a sophisticated Russian-made system positioned to protect the Natanz nuclear installation. In other words, Israel has demonstrated that Iran’s best technology can’t protect the country’s skies from the IDF. As Yossi Kuperwasser puts it, the attack, combined with the response to the assault on April 13,

clarified to the Iranians that whereas we [Israelis] are not as vulnerable as they thought, they are more vulnerable than they thought. They have difficulty hitting us, but we have no difficulty hitting them.

Nobody knows exactly how the operation was carried out. . . . It is good that a question mark hovers over . . . what exactly Israel did. Let’s keep them wondering. It is good for deniability and good for keeping the enemy uncertain.

The fact that we chose targets that were in the vicinity of a major nuclear facility but were linked to the Iranian missile and air forces was a good message. It communicated that we can reach other targets as well but, as we don’t want escalation, we chose targets nearby that were involved in the attack against Israel. I think it sends the message that if we want to, we can send a stronger message. Israel is not seeking escalation at the moment.