As Islamic State is pushed out of town after town in the battle to regain control of Mosul, the world can expect more terrorist attacks elsewhere.It’s not a fault of the campaign, merely a fact. An insecure ISIS is an ISIS more likely to lash out to prove its worth. An ISIS getting pounded by airstrikes or getting run over on the ground needs to show potential recruits it’s still worth joining. They’ll want to underscore evolution, not devolution.Maj. Gen. Gary Volesky, top commander of US ground forces in Iraq, warned days after the battle for Mosul commenced that ISIS can be expected to “go into an insurgency mode” as it loses chunks of its caliphate and will “try to do these high-profile, spectacular attacks to draw attention away from the losses that they’re suffering... to tell everybody, you know, they’re still a relevant organization.”In the months it took to wrest back control of Ramadi, ISIS operatives lashed out with global attacks including Paris, San Bernardino and Jakarta, as well as the downing of a Metrojet flight out of Sharm e-Sheikh with a soda-can bomb.Sure enough, just days into the Mosul offensive there was an attack in the suburbs outside Jakarta. Three cops were stabbed near a high school by a young jihadist who first pinned up an ISIS sticker. The attacker, reported ISIS’ Amaq news agency, was “a fighter of the Islamic State.”When we wage offensives against terrorist groups, they’re going to bite back as much as they’re able. But it’s important to remember, as we strike at the caliphate strongholds, that the evolution of terrorism points not to a terrorist state but insidious growth within established nations. Terrorism spreads not just as a reaction to defeats, or as a fallback strategy after failed battles, but in a homegrown, borderless fashion by design.How ISIS behaves in the coming months will be indicative of its survival strategy. And if it’s planning to survive, it won’t be leaning on its caliphate land grab. By all measures, the “Islamic state” hasn’t been the success it promised. It’s had to cut fighters’ salaries, it’s disappointed foreign fighters who expected more glory and livable conditions, and its fanfare gold currency hasn’t exactly set markets ablaze. They tried to create a functional state by recruiting administrative professionals, but those who signed up for desk duty running the bureaucracy have been run out to the front lines as needed. This hasn’t stopped ISIS from still trying to get recruits to come fight; a recent video targeted Indonesians and exhorted would-be jihadists from the most populous Muslim country to make the trip.ISIS knew it wouldn’t be able to hold on to the caliphate if global powers were to coalesce against it. Al-Qaida knew ISIS wouldn’t be able to hold on to the caliphate, thus didn’t rush to join the party and quietly pushed forward with its own goals. ISIS’ business model is not going well in terms of its goal of sacking Rome by 2020. And losing the Syrian town of Dabiq, another mainstay in their apocalyptic manifesto, also wasn’t on its wish list.But caliphate expansion needs to be viewed in broader terms.The strategic objective of flushing ISIS out of Iraqi territory is not defeating ISIS, but flushing them back into the lawless dictatorship of Syria – where, despite claims one may have heard during the presidential campaigns, neither Bashar Assad nor his Russian ally are doing much of anything to combat ISIS. Instead, they’d rather live like a separated couple under the same roof – when ISIS recently released photos of a training camp in South Damascus, it was apparently their turn to use the backyard.It is necessary to physically crush ISIS in their declared caliphate, particularly to liberate millions of people who have been living under terrifying occupation, threatened against trying to escape, or kidnapped from other regions and held as slaves by the terrorist group.And the attacks against their caliphate turf do have a trickle-down impact on international terrorism – but a small one. On August 17, coalition airstrikes in Raqqa, Syria, killed Abu Ibrahim al-Fransi and Abu Musab al-Fransi, two Frenchmen in charge of a European cell planning attacks.Yet while terrorist talent isn’t always necessarily replenished in the same quality or quantity, it does grow back.And when those terrorists are planted in the most unlikely of neighborhoods around the globe, it’s the kind of expansion that can’t be stopped with a military defeat. The author is a senior fellow with the news and public policy group, Haym Salomon Center. A veteran journalist, Johnson covers the Pentagon, the intelligence community and State Department.Bridget currently serves as DC bureau chief for PJ Media.