After President Donald Trump announced the withdrawal of 2,000 troops from Syria last month, the US military ramped up its bombing campaign against territory still held by the Islamic State of Iraq and the Levant (ISIL) group in the eastern part of the country, according to sources on the ground and photographs obtained in a joint investigation by Al Jazeera and The Intercept.

The fiercest attacks in the past week occurred in Al Kashmah, a village on the Euphrates River near the border with Iraq, according to three sources in eastern Syria. Amid US air attacks and artillery fire by the US-backed Syrian Democratic Forces (SDF), civilians and family members of ISIL fighters fled to villages to the south, the sources said. While Al Kashmah has not yet fallen, the only people remaining there are fighters representing what has become the front line of the war against ISIL in Deir Az Zor province.

The ISIL fighters are clustered in villages along the Euphrates, from the border with Iraq to south of Hajin, a former ISIL stronghold that fell to the SDF, a Kurdish-led militia, in mid-December.

There are about 50,000 to 60,000 people who remain in those areas, according to a civilian activist in Deir Az Zor who documents rights abuses and asked not to be named due to safety concerns. "The civilians in these areas have no place to go or hide from the US bombardment of their villages," the activist said, noting that the residents have been harmed at the hands of the Syrian government, the US and ISIL alike.

Bombing of a hospital

The ISIL-held villages along the Euphrates have been the targets of US bombing sorties since November as part of Operation Roundup. In addition to military targets, Operation Roundup bombed civilian areas, including a hospital, The Intercept and Al Jazeera reported last month.

The US could not attack the hospital without warning it first - and without giving the hospital a reasonable amount of time to either stop ISIS from using it or to evacuate civilian personnel and wounded. Kevin Jon Heller, professor of international law

A senior ISIL fighter said the Yarmouk Hospital was the region’s last public health facility that treated civilians in the area. He also acknowledged that ISIL might have used it to treat its fighters if treatment was not available in its own field hospitals.

Kevin Jon Heller, an international law scholar, told Al Jazeera that the US could not legally attack the hospital simply because it believed some ISIL fighters were there.

"The US could not attack the hospital without warning it first - and without giving the hospital a reasonable amount of time to either stop ISIS from using it or to evacuate civilian personnel and wounded," said Heller, a professor of international law at Australia National University and the University of Amsterdam

Heller said the bombing of a hospital in a combat zone without considering civilian casualties or issuing a warning is a fundamental violation of international humanitarian law, a component of international law that regulates the conduct of war and the protection of civilians.

Trump's abrupt December 19 decision to withdraw US ground troops involved in the fight against ISIL in Syria took even the US Department of Defense by surprise. Speaking to reporters on Wednesday, the president declined to give a timeline for the pullout, and said instead that it would happen "over a period of time." The increased intensity of the bombings, however, belie claims by Trump and others that ISIL has been defeated or that the US war in Syria, which has largely been carried out from the skies, is over. It remains unclear whether US air attacks will continue once the troops leave.

During the final days of 2018, the US campaign bombed villages up and down the Euphrates, focusing primarily on Al Kashmah. On New Year's Eve, the bombs relentlessly assaulted Al Kashmah, leaving the village largely destroyed by the next morning, according to an ISIL fighter who was there. (We interviewed members of ISIL and the SDF, as well as a tribal leader, for this article via messaging services, and we've granted them anonymity because they all stand to be targeted by the various warring factions for speaking to journalists.)

The coalition against ISIL appears to be targeting internet cafes, according to two sources on the ground. Internet cafes in the villages are used by civilians and ISIL fighters alike. They are not part of ISIL’s tactical communications infrastructure, according to sources, but fighters typically use them to communicate with the outside world, especially their families in other countries.

"They just like to disrupt and mess everything up," an ISIL fighter said in an interview. "They bombed the places where they sell gasoline for the motor, or they sell cooking oil, or where they filter the water - they bomb all these places. Not just the net, they bomb everything just to make your life horrible."

The risk of civilian casualties from bombings in Deir Az Zor is high because the rural villages have become densely populated with the families of ISIL fighters and civilians fleeing in recent months from cities and towns that have fallen to Kurdish-led forces. "No building is empty here," the ISIL fighter said, referring to the remaining ISIL-controlled villages in Deir Az Zor. Fighters and civilians in the villages have reportedly been describing the US bombing campaign as a scorched-earth policy, using an Arabic term that translates to "burn the ground".

On Sunday, the US military admitted that it has killed 1,139 civilians in Iraq and Syria since the start of its campaign against ISIL in 2014. That number is significantly smaller than the estimates of civilian casualties put out by monitoring groups, like Airwars, which says that between 7,308 and 11,629 civilians have been killed.

In response to a list of questions about the bombings in Syria, Danielle Covington, a spokesperson for the US Department of Defense, said the coalition dictates "the pace of our strikes against ISIS targets deliberately and with careful consideration of their impact to civilians. The increase in strikes in late December were selected specifically to degrade ISIS capabilities and were unrelated to any other variable."

Following Trump's withdrawal announcement, the Kurds, who lead the on-the-ground forces that had partnered with the US in fighting ISIL in Syria, reached out to President Bashar al-Assad of Syria for protection. Feeling betrayed by the US, the Kurds are concerned about a possible attack by Turkey, which has long feared that its own minority Kurdish population might be emboldened by the existence of a Kurdish state or autonomous region to the south of Turkey. (In March 2018, the Turkish Armed Forces and allied militia seized control of the Syrian city of Afrin from the Kurds.)

In addition, after the evacuation of civilians from Al Kashmah, ISIL negotiated a three-day ceasefire with the Kurds, according to three sources on the ground. On Monday, seven trucks carrying food and humanitarian aid entered ISIL-controlled areas under the agreement, according to one ISIL and one SDF source. The ceasefire was initially scheduled to end on December 31, but ISIL officials are discussing a possible six-month extension, according to an ISIL fighter familiar with the talks but who is not directly part of the effort. During the temporary ceasefire, some ISIL fighters and defectors fled Deir Az Zor to other parts of Syria, according to two sources who made such journeys themselves.

A lasting ceasefire would allow badly-needed supplies to reach civilians in the villages, and ISIL would also use it to regroup. The Kurds would receive a safeguard from a two-front war if the Turks attack.

A ceasefire between ISIL and the Kurds, coupled with the Syrian government's potential protection of the Kurds from Turkey, would largely undercut part of Trump's public rationale for withdrawing US troops from Syria. In a tweet, Trump described how Turkey could "easily take care of whatever remains" of ISIL. In a subsequent tweet, Trump spoke of his conversation with President Recep Tayyip Erdogan of Turkey:

President @RT_Erdogan of Turkey has very strongly informed me that he will eradicate whatever is left of ISIS in Syria....and he is a man who can do it plus, Turkey is right “next door.” Our troops are coming home! — Donald J. Trump (@realDonaldTrump) December 24, 2018

But the prospect of Turkey's completion of a clean-up job against ISIL in Syria seems increasingly unlikely given the rapidly shifting alliances there.

Meanwhile, the US military continues to drop bombs on Deir Az Zor, despite the fact that the Kurds, expected to be abandoned by the US, are not currently engaging ISIL fighters.

"They’ve backstabbed all their allies and they’re killing the people here, and eventually the Islamic State will survive and spread or it will fall," the ISIL fighter said, referring to the US. "But there will be people here who will remember what happened here, and they will carry on this information and it will spread throughout the Middle East."

Follow Ali Younes on Twitter: @ali_reports