Donald Trump says he may keep a small force of US soldiers in Kurdish-controlled Syria to protect the region's oilfields.

Key points: A US-brokered ceasefire between Turkish and Kurdish forces ends on Tuesday night

A US-brokered ceasefire between Turkish and Kurdish forces ends on Tuesday night Donald Trump says some US troops may stay in Syria to protect the oilfields there

Donald Trump says some US troops may stay in Syria to protect the oilfields there Up to 350,000 Kurds have been displaced by Turkey's invasion

The statement from the US President has been taken as another insult by desperate Kurds who are on the run from a Turkish invasion that could resume again on Tuesday night.

Turkey invaded Kurdish areas two weeks ago after Mr Trump said US troops based there would leave and would not interfere with a Turkish attack.

The last convoys of US troops pulled out on Monday to the jeers of locals who feel betrayed by their withdrawal.

Mr Trump is still adamant he has achieved something.

Mr Trump said it would be too dangerous to leave US troops in the country, but some may remain to protect Syrian oilfields. ( Reuters: Leah Millis )

"If they didn't go through two-and-a-half days of hell, I don't think they would have done it," Mr Trump said.

"I think you couldn't have made a deal, and people have been trying to make this deal for years. But we're close to making it."

Mr Trump said they had been fighting for 300 years, seemingly referring to the Kurds and Turkey, who have been at odds for the past 40 years.

"So why should we put our soldiers in the midst of two large groups, hundreds of thousands potentially, of people, and they're fighting? I don't think so," he said.

He said it would be too dangerous to leave US troops in the country, but some may remain to protect Syrian oilfields from Islamic State militants.

"I don't think it's necessary other than that we secure the oil," Mr Trump said.

"We want to keep the oil, and we'll work something out with the Kurds so they have some money … maybe we'll get one of our big oil companies to go in and do it properly."

US Defence Secretary Mark Esper confirmed the Pentagon may recommend to the White House that a small number of troops be left to guard oilfields in eastern Syria.

'Trump is a traitor. He stabbed us in our back'

In a school building in northern Syria, Adla Issa stands over two gas burners, stirring two enormous pots of lentils.

She is making lunch for 200 people, and says conditions at the makeshift refuge are tough.

"My room is so small. I've got five kids; they're sleeping on top of each other. What can we do? God help us," she said.

Like most of the refugees in the Hassaka school, she is a resident of Ras el Ain, a town near the border that has been one of the targets of Turkey's invasion.

Ms Issa has nothing but scorn for the US President.

She cites the pre-dawn departure of US troops stationed on the border, the morning after Mr Trump revealed Turkey would soon be invading.

"Trump is a traitor. He stabbed us in our back, at 4:00am, when they just left. Even if he threatened to behead me, I would tell you the truth. He's a traitor," she said.

Kurdish refugee Adla Issa is making lentils to feed 200 people. ( ABC News: Adam Harvey )

The battle for Ras al Ein is now over, but it is occupied by Turkish-backed militias and these Kurdish and Arab families cannot go home.

"I was in Ras el Ain for three days after the attacks," another evacuee, Khaled Jamal, said.

"They stole my motorcycle. In another home they took everything in the house. They had masked people with them, showing them which homes should be targeted."

Mr Jamal now lives in one of the school's small classrooms with his wife, six children, parents — and two other families.

"With two or three families staying together in the same room, it's very difficult that we are forced to be like this. We are now refugees in our own country," he said.

Khaled Jamal and his family are living in a school in northern Syria which has been transformed into a makeshift refugee camp. ( ABC News: Adam Harvey )

Kurdish authorities estimate 350,000 people have been displaced by Turkey's invasion.

Many of them have moved to Hassaka, which is the closest city outside of the zone that Turkish President Recep Tayyip Erdogan wants to capture.

A water-pumping station supplying Hassaka was damaged in the fighting, and the water that arrives at the school each day is from a nearby dam.

"We don't have water here, the water is too dirty, and there's no clean water to drink. That's why all of our kids are sick," Mr Jamal said.

"We don't have enough electricity here as well. There is a lot of suffering here. We weren't refugees, but we've become refugees."

A temporary ceasefire in Syria is due to end on Tuesday and, if attacks resume, a new wave of refugees will join the families sheltering across the north, and fleeing west to Iraq.