BEIRUT/ANKARA/WASHINGTON: The United States welcomed an apparent pause in fighting between Turkish-backed forces and Kurdish militia fighters in Syria Tuesday, both of them members of the coalition fighting Daesh (ISIS), but it was far from clear that any truce would hold.

Washington has been alarmed by NATO ally Turkey’s incursion into northern Syria, launched almost a week ago. The operation, dubbed “Euphrates Shield,” aims to push back Daesh but also to prevent U.S.-backed Kurdish militia fighters from seizing more territory along the Turkish border.

Ankara fears advances by Kurdish fighters as Daesh is pushed out are aimed at establishing a Kurdish enclave along Syria’s northern border, a move which could embolden a three-decade Kurdish insurgency on Turkish soil.

The Turkish incursion has left Washington scrambling to get its feuding allies to focus their firepower on Daesh instead of each other after clashes that have threatened to unravel the United States’ war strategy in Syria.

“The United States welcomes the overnight calm between the Turkish military and other counter-ISIL forces in Syria,” White House spokesman Josh Earnest said, using an alternative acronym for Daesh. “It continues to encourage these moves as a way to prevent further hostilities and loss of life between all counter-ISIL forces operating in the area.”

A Kurdish military official said a cease-fire between Turkey and Kurdish-backed militia fighters was holding. But Turkish military sources denied there was any such agreement, while a Turkish-backed Syrian rebel commander characterized it only as a “pause” and said that military operations would soon resume.

Turkish-backed forces began their offensive last week by capturing the Syrian frontier town of Jarablus from Daesh; they then advanced on areas controlled by Kurdish-aligned militias, which have U.S. support in battling militants.

Washington said the offensive by its NATO ally risked undermining the fight against Daesh.

French President Francois Hollande, meanwhile, said he understood Turkey’s need to defend itself but that targeting Kurdish forces which were battling militants could further inflame the 5-year-old Syrian conflict.

Ankara says it would not take orders from anyone on how to protect the nation. The Turkish Foreign Ministry said Tuesday military operations in Syria would continue until all threats to Turkish security were removed and that U.S. comments on Turkey’s targets in the operation were “unacceptable.”

“The statements of U.S. officials about the content and the targets of the Euphrates Shield operation ... are unacceptable and are not in line with the alliance between the two countries,” a Foreign Ministry spokesman said, adding that a complaint had been lodged with the U.S. ambassador to Turkey.

Eager to avoid more clashes between Turkey and U.S.-backed Syrian fighters, the Pentagon said the U.S.-led coalition against Daesh was establishing communications channels to better coordinate in a “crowded battle space.”“The improved coordination of armed activities in northern Syria will seek to assure the safety of all forces,” Pentagon spokesman Matthew Allen said.

Sharfan Darwish, a spokesman for the Manbij Military Council, said a cease-fire between Turkey and the Jarablus Military Council was holding.

Both councils are allied with the Syrian Democratic Forces, a U.S.-backed alliance of groups including the powerful Kurdish YPG militia that is fighting Daesh insurgents and has expanded along Syria’s frontier with Turkey.

The Jarablus Military Council subsequently said the temporary cease-fire was “under the oversight of the international coalition led by the United States.”

Two senior Turkish military sources denied any such truce had been agreed. A commander in one of the Turkish-backed Syrian rebel groups that have clashed with SDF-allied groups south of Jarablus also denied such a deal.

“There is no truce and no cease-fire. But there has been a pause for some time,” the commander, who declined to be identified, told Reuters by telephone, adding that the operation would resume shortly.

A U.S. official, speaking on condition of anonymity, also declined to describe the pause in fighting as a cease-fire per se, though he said the intent was similar.

Turkey’s army chief earlier signaled no letup in Ankara’s Syria offensive, saying its successes showed a failed coup in Turkey last month had done nothing to dent the military’s power.

“By pursuing the Euphrates Shield operation, which is crucial for our national security and for our neighbors’ security, the Turkish Armed Forces are showing they have lost none of their strength,” Chief of General Staff Hulusi Akar said in a statement to mark a national holiday.

Meanwhile, Syrian rebels captured the strategic town of Helfaya in northern Hama province in a major offensive that threatens government loyalist towns populated by minority Christians and Alawites north of the provincial capital, rebels and the Syrian Observatory for Human Rights said Tuesday. Helfaya was stormed Monday after the hard-line militant Jund al-Aqsa alongside Free Syrian Army brigades launched a battle overnight that overran several army and pro-government checkpoints in northern Hama countryside.

The town, which is near a main road that links the coastal areas with the Aleppo-Damascus highway is only a few kilometers from the historic Christian town of Mhardeh to the west.

The offensive brought them closer to the army stronghold of Suran, the army’s northern gateway to the city of Hama, the provincial capital.