U.S. President Barack Obama and his French counterpart Francois Hollande on Monday called for a ceasefire between conflicting parties in eastern Ukraine with Russia's full support.
The two leaders, in a phone conversation, agreed that "their preference remains a bilateral ceasefire, fully supported by Russia, and a peaceful resolution to the conflict, including the release of all hostages," the White House said in a statement.
Ukrainian President Petro Poroshenko ended a 10-day ceasefire on July 1 in the country's restive east, blaming the insurgent forces for failing to observe the truce.
The Ukrainian military then resumed its offensive in Donetsk and Lugansk regions by launching air raids on the insurgents.
No breakthrough was made after representatives from Ukraine, Russia and the Organization for Security and Cooperation in Europe met on Sunday, and the Ukrainian troops announced on Monday a plan to besiege Donetsk and Lugansk, two regional capitals under the rebels' control.
The Russian Foreign Ministry on Monday denounced Kiev's shelling and air strikes on Donetsk, Lugansk and Slavyansk with civilian casualties, calling for a European response to the "policy of crime."
In his phone talks with Hollande, Obama voiced his support for Kiev's military moves "in the absence of any meaningful efforts by the separatists to engage in talks or to adhere to the ceasefire," the White House said.
The two leaders urged Russia to stop what they called "destabilizing activities," including allowing and facilitating the transit of weapons and fighters across the border, building up its own military near the border, and halting its support for the separatists.
Russia has dismissed the West's accusations of supplying the Ukrainian rebels with arms as "shameless."