"The operation will start when all preparations are completed," the official, who remained anonymous, said.

Turkish efforts to crush the YPG have been complicated by YPG ties with Russia and the United States, which have both worked with the YPG and another force it leads, the Syrian Democratic Forces (SDF), during the Syrian war.

"We are in coordination with Russia on the matter. The issue was addressed with the United States already," the senior Turkish security official said.

SDF sources say Turkey has stepped up attacks using drones and artillery fired from Turkish territory targeting YPG positions in the last two weeks.

Turkey has mounted three offensives into Syria since 2016 against the YPG, which Ankara deems a terrorist organization due to its links with the Kurdistan Workers' Party (PKK).

Tensions have spiked since two Turkish policemen were killed a month ago in a missile attack in northern Syria which Turkey said was carried out by the YPG. On Oct. 11, Turkish President Tayyip Erdogan said the attack was "the final straw," though Ankara has given no indication an operation is imminent.

After meeting U.S. President Joe Biden in Rome last weekend, Erdogan also said: "When it is time to carry out an operation, of course an operation will be done. There is no stepping back from that."

Meanwhile, Syrian rebels said they are standing by to join Turkey's possible operation. Reuters quoted rebel sources as saying that Turkey recently sent military supplies to its Syrian allies as part of preparations for possible action, and rebel fighters have been redeployed towards areas that are expected to be targeted in any new attack.

"Moving to a state of complete readiness now needs only a short period before any military operation is declared," said Major Youssef Hamoud, a spokesperson for Turkey-backed rebels called the National Army.

Previous Turkish incursions have been preceded by lengthy build-ups and large movements of Turkish forces at the border, which have yet to be observed this time.

Reporter's code: 50101