Andrew McCabe is a former deputy director of the FBI.

I am glad Qasem Soleimani is dead.

Iran’s measured response to the general’s killing has many people believing the worst of this crisis has passed. Should we be relieved? By limiting its response to U.S. military targets, Iran sent a powerful message to its own people that Soleimani’s killing would not go unavenged. Tehran managed to accomplish this without escalating a military conflict with the United States.

However, U.S. intelligence and law enforcement officials would be well-advised to remember that Iran’s most provocative actions have often been asymmetric attacks conducted through proxy forces and terrorist elements. It is those deniable, civilian-focused attacks we should be looking for as this situation unfolds. As a counterterrorism leader for the FBI, it was my job to figure out how events abroad would impact us here. And I am afraid the saga of Soleimani is far from over.

For many years, it was the prevailing opinion of most Iran watchers that staging an attack inside the United States was a red line that Iran dared not cross. We assumed Tehran’s well-founded fear of an overwhelming U.S. response was enough to keep its terrorist plots focused on less capable adversaries.

In 2011, those assumptions were shattered. With the help of an outstanding Drug Enforcement Administration source, the FBI learned that members of the elite Quds Force (then headed by Soleimani), conspired with a dual U.S./Iranian citizen named Mansour Arbabsiar to assassinate Saudi Arabia’s ambassador to the United States. Directing and funding the plot from Iran, Quds Force operatives instructed Arbabsiar to murder the ambassador by setting off a bomb inside a popular Washington restaurant. During a telephone call recorded after Arbabsiar’s arrest, the Quds Force operatives instructed him to “just do it quickly, it’s late.” In 2013, Arbabsiar was sentenced to 25 years in prison for his role in the plot. To this day, his Quds Force handler, Gholam Shakuri, remains an indicted fugitive.

Once we knew Iran would try to launch a terrorism plot inside the United States, the FBI began to take a closer look at Hezbollah. Hezbollah is a Lebanon-based political and terrorist organization supported and directed by Iran. Founded in the early 1980s by the Quds Force, Hezbollah has perpetrated terrorist attacks against American, Israeli and Jewish targets around the world. Before the attacks of Sept. 11, 2001, Hezbollah was responsible for the deaths of more Americans than any other terrorist organization.

Hezbollah plays a long game — inserting trained operatives into foreign countries long before they are needed for an attack. Hiding in plain sight, they collect target intelligence, stockpile explosives and train for the day they are called to act. In 2012, Hezbollah used covert agents to execute attacks in Bulgaria, Thailand, India and the Republic of Georgia. That same year, police disrupted additional plots and seized explosive materials from Hezbollah operatives in Cyprus, Thailand, Azerbaijan and Nigeria. In 2014, Hezbollah operatives were arrested while planning attacks in Bangkok and Peru. In 2015, British authorities discovered thousands of pounds of ammonium nitrate — a key explosive element recovered from ice packs — hidden in four London locations by a suspected Hezbollah member.

Could Hezbollah do this in the United States? We know they can because they already did. In 2017, Ali Kourani and Samer El Debek were arrested in New York and Michigan respectively, and charged with numerous offenses committed while working as agents for Hezbollah. Both were recruited and sent to the United States by Hezbollah’s External Security Organization (ESO); both were trained to use weapons and explosives. Over the course of 15 years in the United States, Kourani collected targeting intelligence on military installations, sought out weapons suppliers for the ESO and corresponded with his Hezbollah handlers through coded messages. An expert bomb maker, Debek lived in the United States while he conducted operations overseas — including cleaning up a Hezbollah bomb factory in Thailand to avoid detection by local authorities. Trained, professional terrorists living and working right under our noses.

On Wednesday, the FBI and the Department of Homeland Security released an intelligence bulletin to law enforcement groups warning them to remain alert to the possibility of Iranian-sponsored terrorist and cyber attacks in the United States. They were right to do so. Iran is unlikely to forget about the death of Soleimani. Despite cool-headed comments lately from Iranian leaders, missiles that missed their marks in the Iraqi desert may not be enough to satisfy their desire for retaliation.

Iran has a long history of striking when their adversaries least expect it. I am confident that our law enforcement and intelligence professionals are working hard to keep us safe. We should help them by remaining vigilant. We may not be out of the woods yet.

Read more: