The Kurdish-led Syrian Democratic Forces announced on Thursday the end of an anti-Islamic State group offensive that started last month aimed at clearing northeastern Syria of militant sleeper cells.
The military campaign began on 25 January with the support of the US-led international coalition fighting IS, dubbed "The Raqqa Martyrs" operation, and saw dozens of suspected IS hideouts in Raqqa governorate raided.
Raqqa was the de-facto capital of IS's self-proclaimed caliphate in Syria and Iraq after 2014. The SDF captured it however in 2017.
"The campaign had a specific time frame and achieved immediate and effective results against the [IS] organisation's movements," the SDF said in a statement.
The SDF is the official military force of the Autonomous Administration of North and East Syria and has fought against IS in the war-torn country alongside US troops. It controls most of Syria east of the Euphrates River.
At least 127 suspected IS members were detained and cells planning attacks were dismantled, the statement added.
The US Central Command (CENTCOM) also said on Thursday it conducted 43 operations against the militant group in Iraq and Syria in January.
The statement broke down the number of operations carried out by US forces alone and those carried out with allied groups, as well as the number of IS members killed and detained.
"While our efforts have degraded ISIS, the group's vile ideology remains uncontained and unconstrained," said CENTCOM commander Gen. Michael Kurilla.
"ISIS continues to represent a threat to not only Iraq and Syria, but to the stability and security of the region," the statement quoted him as saying.
At the end of last year, CENTCOM said IS had an 'army' of fighters held at detention facilities in Iraq and Syria, according to the US military.
Despite the fall of its self-proclaimed caliphate, IS continues to wage a low-level insurgency in Iraq and Syria, and claims attacks in both countries.
Several military and security personnel and civilians have been killed in hit-and-run or bomb attacks.
The conflict in Syria is believed to have killed more than half a million people and displaced millions more, leaving many parts of the country in ruins mostly due to Assad regime and Russian artillery and airstrikes.