Just a few months ago, analysts and policy-makers were certain that the defeat of Islamic State (IS) forces was simply a matter of time.

Coalition airstrikes would degrade the group's capabilities and eventually allow Iraqi forces and Kurdish Peshmerga — though discredited by their poor military showing in mid-2014 — to push back the extremists. And indeed, IS fighters were ejected from Tikrit in March 2015 by the Iraqi army and thousands of motivated fighters from Shia militias. In Kobani in northern Syria, IS fighters were defeated by Syrian Kurdish fighters. Elsewhere in the country, the regime of Bashar al-Assad was going on the offensive with help from Hezbollah and advisers from the Iranian Revolutionary Guard.

The Islamic State, however, rose like a phoenix from the ashes of every setback. And today, the situation is not so rosy.

The victories against IS in early 2015 have proven ephemeral — or have been nullified by IS gains elsewhere. On Sunday, CIA director John Brennan said on Face the Nation, "I don't see this being resolved anytime soon." Assad's vaunted offensives of February 2015 have fallen short as the regime faced stiff resistance from a wide variety of opposition fighters, including elements from IS. The failure was alarming in part because the campaign was designed and aided by both Hezbollah and the Iranians, two seemingly ascendant Shia powers.

The Syrian regime's resources are stretched thin and the rate of desertion among its military is increasing; in short, it is running out of manpower to face the myriad opposition factions in set-piece battles. The Alawites, the sectarian community that dominates the top echelons of the regime, are circling the wagons and building popular militia forces to defend their own turf rather than seeking to re-conquer lost territory — IS now reportedly controls half of Syria — in the eastern and southern parts of the country. The appearance of IS fighters in Palestinian refugee camps on the outskirts of Damascus, along with the fall of Tadmor — the modern city on the site of Palymra — merely intensifies the sense of doom and gloom in Damascus.

The situation in Iraq is just as complicated, something that the Obama administration appears either oblivious to or reluctant to acknowledge. Much of the US strategy continues to hinge on what is increasingly a mirage: a unified, albeit federal, Iraq under the control of Baghdad. Meanwhile, the resilience of IS is greatly enhanced by the ability of its military forces to innovate and adapt faster on the ground than its lackluster opponents.

In light of the constant aerial strikes by the US and its allies, IS has dispersed and made its forces more mobile, no longer presenting dense concentrations of fighting men as it did when it seized Mosul in mid-2014. Instead, when IS seized Ramadi in May 2015, it made use of inclement weather and sent several small units from different directions simultaneously into the city aided by suicide bombers. Moreover, the fact that the group faced ill-equipped and poorly motivated Sunni fighters in and around Ramadi did not do anything for Baghdad's standing with the country's already alienated Sunni community, which had pleaded for arms while caught between the unfathomable brutality of IS and revengeful Shia militias.

Many Sunnis are now angling for their own "super-region," one that would have considerable independence from Baghdad. The problem? In order to have it, the Sunnis would need to first defeat IS. Currently, they're unable to do so because they lack the resources; despite all the talk from Baghdad and Washington about arming Sunni tribes, Baghdad is not actually keen to do so.

And besides, the Sunnis seem relatively ambivalent about defeating IS. They took an unequivocal stance between late 2006 and 2009, when they joined with the Americans and the Iraqi government to deal the Islamist militants what was then seen as a decisive blow. Now, however, despite Sunnis' resentment and fear of IS, the Islamists' existence is seen as a kind of insurance policy against Shia revanchism should Baghdad succeed in retaking the three Sunni provinces of Anbar, Salahuddin, and Ninevah.

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VICE News documented the early days of the caliphate in 'The Islamic State.'

The "victory" of the Iraqi government in Tikrit was more propaganda than reality; a few hundred IS fighters managed to inflict considerable damage on the Shia militias that had been mobilized to fight alongside the Iraqi army, then withdrew because they were outnumbered and wished to avoid being surrounded. The IS forces in Tikrit simply felt that they had done enough damage; there was no need to waste further assets in an untenable situation.

Militarily, the Iraqi Shia militias are better motivated and more dedicated than the regular army. Anecdotal information out of Baghdad suggests that Iraqi Shias are wondering whether the government should invest more effort building these forces into an effective and more organized parallel army. Even that parallel army, however, might be reluctant to commit to any significant long-term offensive to reclaim provinces full of "ungrateful" Sunnis.

But the Shia are willing to die to defend what they have, and there is increased sentiment among the Shia in central Iraq and Baghdad, along with the southern part of the country, that they would be better off without the Sunnis. There also exists the belief that the Kurds have more or less opted out of the Iraqi state despite the fact that they maintain a presence within the government in Baghdad. The Shia would seemingly not be sorry to see them exit the government in a deal that would settle as best as possible divisions of resources and territory. However, whether the Kurds would take the plunge and opt for de jure rather than de facto independence is a question that is subject to regional realities — How would Ankara and Tehran react? — rather than merely a matter of a deal between Baghdad and Erbil.

The Islamic State will continue to be a profound geopolitical problem for the region and the international community, and a long battle lies ahead. Syria and Iraq are more or less shattered states; it is unlikely that they will be put back together in their previous shapes. If Assad survives 2015, it will be as head of a rump state of Alawites and other minorities protected by Hezbollah, Iran, and Alawite militias. Shia Iraq will survive, and will possibly dissociate itself from the nettlesome Sunni regions. The Kurds will go their own way step by step. The international community is currently at a loss for how to stem the flow of foreign fighters to the IS battlefields — and even more serious is the growing sympathy and admiration for the group in various parts of the world among disgruntled and alienated youth.

If the US is serious about defeating IS, it needs to take on a larger share of the fight on the ground. This means more troops embedded with regular Iraqi forces in order to bring about better command, control, and coordination. It also means advisors who can continue to train these forces so that they improve over time. If this is not done, the regular Iraqi military will continue to be nothing more than an auxiliary to the more motivated — and pro-Iranian — Shia militias. Currently, militia commanders are giving orders to the regular military; that cannot be good for morale.

If the world is not serious about taking on and defeating IS, we can expect the group to continue to consolidate itself and expand its territory opportunistically. IS does have problems with consolidating its authority over the areas it rules; while it has to fight to maintain its ideological raison d'etre, it also has to provide services for the people over which it holds sway. While the two are not mutually exclusive, doing both becomes a resource and personnel enterprise that the militants may not be able to sustain. Given its own internal ideological and expansionist dynamics, the group's future hinges on continuing to fight.

This month, the Islamic State celebrates the first anniversary of its self-declared caliphate. The group has little reason to fear it will be the last.