The US military says it has struck an al Qaeda leadership and training facility in northern Syria where attacks against Americans and others were being planned.
The US-led coalition said on Monday its aircraft carried out a strike in north-western Syria a day earlier – strikes that a monitor said killed eight militants, including commanders, from an Al Qaeda-linked group.
"This operation targeted AQ-S operatives responsible for plotting external attacks threatening US citizens, our partners, and innocent civilians," US Central Command said in a statement, using an acronym for Al Qaeda in Syria.
The Syrian Observatory for Human Rights, a Britain-based war monitor, said six commanders were among the slain militants from the Hurras al Deen group in Aleppo province.
The killed commanders included two Tunisians, two Algerians, an Egyptian and a Syrian, the Observatory added.
"With our allies and partners, we will continue to target Daesh and Al Qaeda to prevent both groups from using Syria as a safe haven," US Central Command said.
Hurras al Deen maintains ties to Al Qaeda and fights alongside the global terrorist network's former Syria branch, Hayat Tahrir al Sham – which dominates most of Idlib province as well as parts of neighbouring Hama, Aleppo and Latakia.
Since its formation in 2014, the US-led coalition against Daesh has targeted militant leaders in Syria's north-west, but the strikes have dropped off significantly since 2017.
In March 2017, the Observatory said a US-led strike on a mosque in the north of Aleppo province killed 49 people, most of them civilians.
The Pentagon denied that large numbers of civilians were killed or that it had targeted the religious building, acknowledging only one possible civilian death.
The greater Idlib area was supposed to be protected by a buffer zone under a September agreement between Russia and Turkey.
But backed by its ally Moscow, Damascus has since late April ramped up its bombardment of the region, home to some three million people – nearly half of whom have been displaced from other parts of Syria.
That came after HTS took over administrative control of the Idlib region at the start of the year.
Hurras al Deen was established in February 2018 and has some 1,800 fighters, including non-Syrians, according to the Observatory.