US President Donald Trump this week took to social media and indicated his decision to bring American troops back home from Syria with a proclamation that the US-led coalition had accomplished the last phase of fight against the remnants of ISIS (Islamic State of Iraq and Syria) and wound up a four-year war against the jihadist group in Syria successfully.

Indicating his desperation to withdraw, Trump tweeted: “Does the USA want to be the Policeman of the Middle East, getting NOTHING but spending precious lives and trillions of dollars protecting others who, in almost all cases, do not appreciate what we are doing? Do we want to be there forever?”

Proclaiming an American victory over ISIS in Syria, Trump said in a video, “Our boys, our young women, our men, they’re all coming back and they’re coming back now. We won, and that’s the way we want it. And that’s the way they want it.”

For many foreign-policy observers these gestures may arouse skepticism, as there has been no reference to a timeline for US withdrawal and it is also not the first time that Trump has spoken of troop withdrawal from conflict-ridden countries such as Syria and Afghanistan.

Nevertheless, on the other side, concerns are simmering over the news of the US withdrawal in several quarters. US Defense Secretary Jim Mattis, who reportedly holds a different worldview from that of the president, tendered he resignation from the administration soon after Trump revealed his Syria-pullout plan.

It is noteworthy that a major partner of the US in the war against ISIS – the Syrian Democratic Forces (SDF), an alliance of Syrian Kurdish and Arab fighters – while launching ground offensives against ISIS had banked on US air strikes to gain victory over the jihadist group.

However, the SDF in a statement has expressed concerns that the withdrawal would “negatively impact” the anti-ISIS campaign and allow the group “to revive itself again.” Further, a major concern for the alliance would be Turkey, which has been worried about alleged links between the Kurdish fighters (YPG militia, the main fighting force in the SDF) and terrorists on its soil might launch a military operation against the fighters.

Meanwhile, many allies as well as senior US Republicans have expressed their disagreement with the claim that victory over ISIS has been complete, believing that while US troops have been able to liquidate the jihadist group in much of Syria’s northeast, many fighters remain in certain pockets of the country.

Concerns have been expressed as to the future of the United States’ Middle East policy, which has been to contain Iran’s regional influence and Russian sway in the region. It has been argued that a US withdrawal could leave a dangerous vacuum to be filled by these actors along with a revival of ISIS. To further skeptics’ concerns, Russian President Vladimir Putin has praised Trump’s decision to withdraw American troops from Syria and agreed that ISIS has been defeated on the ground.

While the town of Hajin, in desert terrain along the Euphrates River’s east bank, was considered the last retreat for the group, there were reports that pointed to ISIS’ presence in other areas such as south of the Euphrates and near the city of Palmyra – areas under the control of the Syrian government and out of the effective reach of US-led coalition troops.

Some US intelligence reports have remained ambivalent as to the strength and number of the group, and reports from the United Nations have suggested that the radical group remained active in rural pockets and border areas of Iraq and Syria even though the US-led forces might have liquidated it in urban strongholds in Mosul and Raqqa.

A report from a UN panel of experts noted: “ISIS has up to 30,000 members roughly distributed between Syria and Iraq and its global network poses a rising threat.”

The reports also came up with a caveat that notwithstanding “ISIS’ battlefield losses, the core will survive with support from countries such as Afghanistan, Libya, Southeast Asia and West Africa.”

Although Trump pledged last April to bring the troops back home from Syria, he backed away from that plan amid confusing signals related to the sway of ISIS. The group’s emir Abu Bakr al-Baghdadi had pointed to the unprecedented capacity of the group to bounce back when he said it could be able to mobilize more than 60,000 fighters in Iraq from more than a hundred countries to its cause when a surge in US troops’ operations in 2007 downsized the group to only about a thousand fighters.

Is battlefield success enough?

Despite battlefield successes, ISIS was reportedly still active in certain pockets of Iraq allegedly because of simmering disaffection, anger and frustration, and alienation among the Sunnis as a result of a palpable tilt in the US-brokered power-sharing arrangements in favor of the Shiite majority. It has been observed that countries such as Iraq, Syria and Afghanistan where ISIS activism became major international concerns are deeply sectarian and the intervening powers were palpably failing to provide sectarian equilibrium and stability.

In Iraq, insurgency was seen gathering momentum when the intervening power fed into Sunni disillusionment by reserving key governmental ministries and posts for Shiites. Even when the US-supported Iraqi regime was able defeat the insurgency on the battlefield, it failed to address its roots, which helped transform the rebellion rather than ending it.

In Syria, similarly, the regime of President Bashar al-Assad, supported by Russia and Iran, is poised to retake lost territory by defeating rebels, but that is not likely to end insurgency. Going by the Iraqi example, there is high probability that the anger and disillusionment of the rebels will find a way out by channeling these negative feelings and energies toward support for ISIS.

The US drive against terror groups has so far engendered mixed results as liquidation of one group has given birth to another group, as in the case of al-Qaeda’s liquidation leading to the rise of ISIS. The jihadis regroup and emerge from another location, either as a reincarnation or by being recruited by another group. In the process, they learn from one another’s modi operandi, share arms and ammunitions, and raise funds from coordinated trade in illegal drugs and arms.

The will and capacity of the US and other powers to address the problem of terrorism in real terms will be contingent on their efforts toward providing for a stable Syrian state with normal socio-economic functions.