UNITED NATIONS (AP) — The United Nations said Friday it is implementing "a gradual return" of the U.N. peacekeeping force to the frontier zone between Syria and the Israeli-occupied Golan Heights.

U.N. deputy spokesman Farhan Haq told reporters that a key goal in the return of the peacekeeping force, known as UNDOF, is reopening the Quneitra crossing between the two sides.

"The ultimate goal for UNDOF is the full return, conditions permitting," he said.

U.N. peacekeepers returned Thursday for the first time in years to the Syria-Israel frontier, conducting joint patrols with Russian military police in a reflection of Moscow's deepening role in mediating between the decades-old foes in the volatile region.

Haq said "the Aug. 2 patrol to the Quneitra crossing point is part of UNDOF's ongoing efforts to return incrementally to the area of separation."

Russian military police have been deploying in all areas recaptured from rebels by the Syrian government, and they have deployed on the edge of the Israeli occupied Golan Heights in the past two days — a move that also appears aimed at reassuring Israel.

Israel considers Iran's growing influence in Syria — it has advisers and allied militias fighting alongside Syrian troops— as an existential threat and had looked for guarantees from Moscow to push pro-Iran fighters away from its frontiers.

Haq stressed that the Russians are not part of UNDOF, which has been authorized to patrol the buffer zone between Syria and Israel since 1974, a year after the Arab-Israeli war. He said the 1974 Disengagement of Forces Agreement state that UNDOF's members cannot include the five permanent members of the U.S. Security Council — the U.S., Russia, China, Britain and France.

For nearly four decades, UNDOF helped enforce a stable truce between the two countries but the seven-year Syrian war moved into the zone not only with intense fighting but the abduction of peacekeepers by al-Qaida-linked anti-Syrian government militants.