French President Francois Hollande, Germany's Chancellor Angela Merkel, Russian President Vladimir Putin, and Ukranian President Petro Poroshenko spoke on the phone Thursday evening, hours after a deal was sealed between Moscow and Kiev to resolve their natural-gas feud.

The Organization for Security and Cooperation in Europe, a 57-nation group that is monitoring the Sept. 5 cease-fire, requested drones from its member countries to keep track of events on the ground.

France and Germany said they would consider providing them. But their request to safeguard the drone operators could run into resistance at the OSCE, a civilian organization that includes Russia, which would have to agree to the plan.

Write to Noemie Bisserbe at noemie.bisserbe@wsj.com

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