(AFP) US-backed Syrian fighters and Iraqi forces on Thursday pursued twin assaults against the Islamic State terrorist group (ISIS), but experts warned the battles will be drawn out.
The offensives on key regions of ISIS-held territory are the two most significant ground efforts against the jihadists since they formed a self-styled "caliphate" in 2014.
In Syria, an alliance backed by the US is fighting to dislodge ISIS north of the jihadist group's bastion in Raqqa city.
The Syrian Democratic Forces are a seven-month-old alliance dominated by Kurdish fighters but also including Christian, Muslim and Turkmen fighters.
They are working their way through small villages and agricultural plains lying south of the town of Ain Issa, which lies less than 60 kilometers (40 miles) north of Raqqa city.
An SDF statement distributed to journalists on Thursday said their forces had "advanced seven kilometers from Ain Issa and liberated five villages and four fields."
Outside the town of Fatsah, bearded SDF field commander Baraa al-Ghanem said the front line now lies "about eight or nine kilometres from the edge of Ain Issa."
"We liberated the villages of Fatsah, Namroudiya, and Wastah as well as several fields. The coming battle will hold a lot of big surprises," he told AFP.
The Syrian Observatory for Human Rights said SDF fighters on Thursday were shelling ISIS positions near Ain Issa as warplanes from the US-led coalition carried out nearly non-stop air raids.
Tunnel, car bombs
But Observatory head Rami Abdel Rahman said the SDF had yet to seize any major strategic positions.
"The battles are in small villages and fields where there are no civilians," he told AFP.
ISIS was also "concentrating 2,000 fighters along the front lines north of Raqqa.
"IS has prepared for this fight in recent months by digging tunnels and lining them with explosives, as well as preparing car bombs and hiding in buildings among civilians," Abdel Rahman added, using another acronym for the group.
The SDF has insisted its current campaign is only for the rural area north of Raqqa city - but ISIS's de facto Syrian capital is expected to be the end goal.
"The ultimate purpose is Raqqa city. It may not be short-term or mid-term, but besieging the city and blocking IS movements is also very important," said Washington-based analyst Mutlu Civiroglu.
Iraqi troops backed by pro-government militias have been advancing towards the city from surrounding areas.
As they close in on the city, the UN's humanitarian coordinator in Iraq said she was receiving "distressing reports" of trapped civilians unable to flee.
The UN said that only 800 people of an estimated 50,000 had been able to flee Fallujah since May 22, "mostly from outlying areas".
Lise Grande said those who managed to escape described limited food supplies, inadequate medication and unsafe drinking water.
Iraqi Prime Minister Haider al-Abadi urged demonstrators not to gather in Baghdad on Friday as security forces were occupied with the Fallujah operation.
Protesters, mostly followers of powerful Shiite cleric Moqtada al-Sadr, have demonstrated for weeks to demand a government reshuffle.
The US and its allies in the fight against ISIS have set their sights on Raqqa, Fallujah, and eventually Mosul in their bid to defeat the jihadists.
But experts warned that ground efforts are likely to be drawn out and complicated.
"The challenges involved in weakening and dislodging the Islamic State from long-held fortified positions are enormous," wrote the New York-based Soufan Group.
To definitively defeat ISIS, Iraqi and Syrian fighters would have to address local concerns, sectarian politics, and ethnic divisions.
The Soufan Group said recapturing Fallujah "poses the biggest military challenge Iraqi forces have faced in the two years" since ISIS seized Mosul, their main Iraqi city.
In Syria, it wrote, ISIS fighters' "determination" to defend Raqqa will make the fight to retake it "one of the fiercest yet."
And ethnic considerations are also complicating the effort, as much of Raqqa province is populated by Sunni Arabs while the SDF is a Kurdish-majority force.
"Any liberating army made up of primarily Kurdish fighters will not be seen as liberators," the Soufan Group warned.