US warplanes continue their unauthorized strikes in Syria, shooting down a pro-Syrian drone near the Jordanian border and killing 17 civilians in the northern province of Raqqah.

According to Colonel Ryan Dillon, the spokesman for the US-led coalition in Syria, a US airstrike hit the drone near the coalition's al-Tanf garrison close to the Jordanian border on Thursday.

Dillon said although the missile the drone had fired hit only dirt and no one was hurt, it was meant to target coalition forces patrolling outside a so-called "deconfliction zone."

The drone was about the same size as a US MQ-1 Predator and it is not immediately clear who owned the aircraft, Dillon pointed out.

The US has declared the surrounding 55 kilometers around the town of al-Tanf a deconfliction zone, in which only forces allied to Washington are allowed entry. The US has not received any permission from Damascus for the move.

It was the third time in less than a month that the US-led forces struck pro-Syrian forces near al-Tanf.

The US decision to establish the deconfliction zone comes as Russia, with backing from Turkey and the Islamic Republic of Iran, brokered a deal for establishing "de-escalation zones" in mainly militant-held areas of Syria during ceasefire talks in the Kazakh capital city of Astana in early May.

Read more:

The plan, which came into effect at midnight on May 5, calls for the cessation of hostilities between militant groups and Syrian government forces.

It covers the northwestern Syrian province of Idlib, northeastern areas of the western coastal province of Latakia, western areas of Aleppo province and northern areas of Hama province.

It also applies to the Rastan and Talbiseh enclave in Homs province, Eastern Ghouta district in the northern Damascus countryside as well as the militant-controlled southern part of the country along the border with Jordan.

File photo of a US-led coalition airstrike in Raqqah, Syria

US airstrikes kill 17 civilians

Meanwhile, the US airstrikes in Syria continue to claim the lives of the civilian population.

According to the so-called Syrian Observatory for Human Rights monitor, 25 US airstrikes on the northern Syrian city of Raqqah and its suburbs killed at least 17 civilians on Thursday.

Dozens of civilians were also wounded during the attacks and the death toll could go even higher, the monitor pointed out, adding that the US warplanes used internationally-banned white phosphorous in the night attacks on Raqqah.

The US has been conducting the airstrikes against what it calls Daesh positions inside Syria since September 2014 without any authorization from the Damascus government or a UN mandate. The attacks have claimed the lives of hundreds of Syrian civilians over the past two months.

On May 23, the US carried out air raids on the city of Mayadin in Dayr al-Zawr province, with the Syrian Observatory for Human Rights saying at least 106 civilians, including 42 children, were killed in the attacks.

The latest US airstrikes come two days after pro-Syrian government forces entered Raqqah province as part of their major offensive to recapture the main stronghold of Daesh Takfiri terrorists in the Arab country.

The pro-government forces retook two villages of Kharbah Mohsen and Beir al-Saba on their way toward Raqqah city.

In addition to the Syrian army’s advance on Tuesday, the so-called Syrian Democratic Forces, a US-backed alliance of mostly Kurdish and Arab militants, said it had launched an operation aimed at pushing Daesh out of Raqqah.