Ukraine and pro-Russian rebels appeared increasingly close to signing a deal to end four months of fighting, as NATO leaders expressed support for Ukraine at a NATO summit Thursday.
Ukrainian President Petro Poroshenko said he's ready to order a cease-fire in the east Friday if a peace deal is signed that day at talks in Minsk, Belarus. The rebels also said they were ready to declare a truce Friday if an agreement with Ukraine is reached on a political settlement for the mostly Russian-speaking region.
Poroshenko discussed the outlines of a deal with Russian President Vladimir Putin on Wednesday, and they both voiced optimism about reaching an agreement in Minsk.
Facing major challenges with conflicts in Ukraine, Syria and Iraq and a winding down of operations in Afghanistan, NATO leaders gathered for a two-day summit at a golf resort in southern Wales. Before the official proceedings began, Poroshenko attended a meeting with Obama and the leaders of NATO's four major European powers: British Prime Minister David Cameron, French President Francois Hollande, German Chancellor Angela Merkel and Italian Prime Minister Matteo Renzi.
A White House official said Obama and the other leaders expressed solidarity with Ukraine and agreed Russia should be punished for its conduct in Ukraine.
"The leaders reiterated their condemnation of Russia's continued flagrant violation of Ukraine's sovereignty and territorial integrity, and agreed on the need for Russia to face increased costs for its actions," U.S. Deputy National Security Advisor Ben Rhodes said. "The leaders also expressed their strong support for President Poroshenko's efforts to achieve a peaceful resolution to the conflict."
Later in the day, Poroshenko was to meet with the heads of state and government from all 28 NATO member states, even though NATO officials have made clear that membership for Ukraine isn't in the cards anytime soon.
In Moscow, Russian Foreign Minister Sergey Lavrov warned reports that Ukraine was seeking to join NATO were "a blatant attempt to derail all the efforts" to seek a peaceful solution to the fighting.
Russian-backed separatists have been fighting government troops in eastern Ukraine since mid-April in a conflict that the U.N. estimates has killed nearly 2,600 people.
A NATO senior official told Sky News that 3,000 Russian combat troops and hundreds of armored vehicles are inside Ukraine.
"We are still seeing several thousand Russian combat troops on the ground inside Ukraine, equipped with hundreds of tanks and armoured vehicles, so [there is] no substantial change in the disposition of Russian forces inside Ukraine," the official said.
The official added that Russian troops in Ukraine will soon outnumber the rebels and there around 20,000 Russian troops near the country’s border.
Rebels have made substantial advances against Ukrainian forces over the past two weeks, including opening a new front along the Sea of Azov coast. That offensive has raised concerns the rebels are aiming to seize Mariupol, a major port of about 500,000 people, and create a land corridor between Russia and Crimea, the Black Sea peninsula that Russia annexed in March.
An AP reporter saw three military-type vehicles ablaze Thursday in Berezove, a village along the main road connecting Mariupol with Donetsk, the largest rebel-held city. Rebel fighters were on the move, indicating they could be trying to take control of the strategic highway. Later, columns of smoke rose outside the nearby village of Olenivka, suggesting that Ukrainian forces were trying to retake it.
Specifics of the hoped-for peace deal are yet to be finalized. Putin has suggested that rebels halt their offensive while the Ukrainian government forces should pull back away from shelling residential areas.
Poroshenko, in his turn, called for the withdrawal of foreign troops, a diplomatic reference to Russian forces, as well as establishing a buffer zone on the border and releasing all Ukrainian prisoners held in Russia.
Both sides have expressed readiness for international monitoring of the truce and a prisoners' exchange.
Earlier, NATO Secretary General Anders Fogh Rasmussen accused the Russians of continued meddling in eastern Ukraine.
"What counts is what is actually happening on the ground," Rasmussen said Thursday. "And we are still witnessing, unfortunately, Russian involvement in destabilizing the situation in eastern Ukraine. So we continue to call on Russia to pull back its troops from Ukrainian borders, stop the flow of weapons and fighters into Ukraine, stop the support for armed militants in Ukraine and engage in a constructive political process."
The battles have taken a heavy toll on Ukraine's army. National Security Council spokesman, Col. Andriy Lysenko, told reporters Thursday that 837 Ukrainian servicemen have been killed and 3,044 wounded since the fighting began in April.
The Associated Press contributed to this report.