NEWPORT, Wales (AP) -- Ukraine's president expressed "careful optimism" Thursday that a peace deal could be reached with Russian-backed separatists at their upcoming talks, even as he and NATO leaders agreed that Moscow should be punished for its role in the insurgency.
President Petro Poroshenko said he was ready to order a cease-fire in eastern Ukraine if a deal is signed at scheduled talks Friday in Minsk, Belarus. The rebels said they were ready to declare a truce if agreement can be reached on a political settlement for the mostly Russian-speaking region.
"Look, Ukraine is fighting for peace," Poroshenko told a news conference, speaking in English. "It's Ukraine which pays the highest price every single day, losing lives of soldiers, innocent civilians."
As head of state, Poroshenko said he is "ready to do my best to stop the war," and he voiced "careful optimism" about the meeting.
Before flying to Wales for the meetings with NATO leaders, Poroshenko discussed the outlines of a peace deal with Russian President Vladimir Putin, who also expressed optimism about the chances of reaching agreement.
For all the upbeat assessments, however, NATO Secretary-General Anders Fogh Rasmussen was skeptical of Russian motives.
"If recent statements from President Putin represent a genuine effort to find a political solution, I would welcome it because that's exactly what we need: a constructive political process," Rasmussen said. "However, what counts is what is actually happening on the ground, so it remains to be seen what it is, and I have to say that previously we have seen similar statements and initiatives and they have been a smoke screen for continued Russian destabilization of the situation in Ukraine."
Since mid-April, Moscow-backed separatists have been fighting government troops in a conflict the U.N. estimates has killed nearly 2,600 people. On Thursday, a NATO military officer told The Associated Press the ranks of Russian soldiers directly involved in the conflict have grown.
"Our current assessment is that several thousand Russian combat troops are actively engaged in fighting in Ukraine," said the officer, who spoke on condition of anonymity because he was not allowed to make public remarks on intelligence matters. NATO previously had put the number of Russians at 1,000.
Russian forces "are equipped with a spectrum of combat capabilities, including hundreds of tanks and armored vehicles, as well as artillery and combat support elements," the NATO officer said.
Kremlin officials repeatedly have denied their troops or military assets are involved.
Facing major challenges with simultaneous conflicts in Ukraine, Syria and Iraq and a winding-down of operations in Afghanistan, NATO leaders began a two-day summit at a golf resort in southern Wales. Before the official proceedings started, Poroshenko met with President Barack 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 Western leaders expressed solidarity with Ukraine and agreed Russia should be punished for its conduct.
"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."
Rhodes told reporters the U.S. and European Union were coordinating on additional sanctions against Russia that could be levied "in the days to come."
Poroshenko also met 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, and that NATO cannot and will not provide it with weapons.
To aid Ukraine's military, NATO leaders instead agreed on a 15 million euro ($20 million) package to help in the areas of cyberdefense, logistics, rehabilitating soldiers injured by the rebels, and command, communications and control capabilities.
Poroshenko also said many individual NATO countries declared their willingness to provide greater support for Ukraine, including "military-technical cooperation on non-lethal and lethal items." Some of the bilateral consultations covered "high-precision weapons," he said.
The news conference ended before reporters could ask additional follow-ups. NATO officials said they couldn't confirm or deny that some member counties had decided to furnish arms to Ukraine.
Specifics of the hoped-for peace deal have yet to be finalized. Putin has suggested that rebels halt their offensive while the Ukrainian government forces should pull back from shelling residential areas.