In the absence of U.S. global leadership and, where necessary, its forces, along with a real, long-term alternative to the terrorists’ allure as a regional and global actor, the gains made these past three years against ISIS remain fragile and incomplete, and could easily unravel, writes John R. Allen. This piece originally appeared in the Washington Post .

Four years ago, just before President Barack Obama appointed me his special envoy to the coalition fighting the so-called Islamic State, I laid out a set of ideas for how to defeat and ultimately destroy the terrorist group. Because the Islamic State was a regional and global problem, posing an imminent threat to the United States, it was clear that its defeat would require an international coalition.

I recommended that this coalition, once formed, be tasked with halting the group’s forward momentum, empowering indigenous forces to be the final and lasting agents of the Islamic State’s defeat, and coordinating much-needed stabilization efforts once the fighting had subsided. I believed then, and remained convinced after taking on the role of special envoy, that only through a comprehensive and multilateral approach could the Islamic State be truly eliminated from the world stage.

Ultimately, the broad strategy executed by the Obama administration and largely continued by the Trump administration was a success—the Islamic State was halted in its tracks and was slowly but surely rolled back in Iraq and Syria. Yet, President Trump’s recent decision to announce the defeat of the Islamic State and pull U.S. forces from the region demands that we confront the question: After more than three years of the coalition campaign against the group, what is the condition of the Islamic State today?

The answer requires a bit of context. After splitting with the al-Nusra Front in the chaotic Syrian battlespace of 2014 and styling itself as a caliphate, the Islamic State quickly grew into a well-coordinated, internationally focused group. Fueled in part by a striking adeptness at digital propaganda that attracted thousands of foreign fighters to its ranks, the group evolved into a three-headed monster—with a core territory spanning Iraq and Syria; with control of discrete external territories in Asia and Africa; and with a permanent and highly sophisticated presence online.

Today, the core Islamic State has lost most of its contiguous territory and nearly all of its subjugated population in Syria and Iraq. Islamic State fighters in Syria still number in the thousands, though their unit integrity has been vastly diminished by coalition firepower and by the Syrian Democratic Forces on the ground. In fact, were it not for the 60,000 coalition-trained indigenous forces operating in northeast Syria, roughly one-third of that country would still be under the caliphate’s control. In Iraq, the Islamic State is essentially defeated, but, as in Syria, hundreds of its fighters have melted into a Sunni landscape still wracked with political chaos.

In outposts in Africa, Central Asia and Southeast Asia, however, the caliphate is anything but defeated, and is, in fact, barely degraded. U.S. and coalition special operators and intelligence assets are helping to battle these groups, but this is a long-term fight relying largely on local actors. Each of the Islamic State’s more than three dozen outposts has the capacity for local violence and could evolve into platforms for larger attacks at any time. The Christmas Eve blast in Kabul, which killed 43 people, was the work of Islamic State forces entrenched in Afghanistan and Pakistan, and is a telling example of their capabilities.

Finally, the caliphate is alive and well across the Internet, spewing its toxic message and recruiting youth globally. Its cyberdomain affords the Islamic State a truly frightening and enduring presence beyond the reach of traditional forces, giving it the capacity to inflict mayhem long after it has been neutralized on the ground. International efforts to mitigate the Islamic State’s online influence have been a major and ongoing challenge, with encrypted messaging apps making traditional analysis, counterintelligence and countermessaging efforts exceptionally difficult. The Islamic State’s cyberpresence remains a potent tool for generating support nearly anywhere in the world and seemingly at random. Indeed, the ongoing threat of directed or inspired “lone wolf” attacks is directly linked to the group’s online campaign.

To be clear: The Islamic State is not defeated. It remains a local, regional and global threat, and notions to the contrary are misinformed. Though coalition efforts have successfully degraded the Islamic State’s core territories, the departure of U.S. forces leaves the door wide open for the group’s resurgence. Even if, as some reports indicate, this departure may be more drawn out than initially expected, the damage done by the broader message—the abandonment of our local partners and others in the coalition—remains unchanged.