Kim Hjelmgaard

USA TODAY

NEWPORT, Wales — Ukrainian President Petro Poroshenko won NATO's support Thursday as he and pro-Russian rebels voiced hope they could reach a cease-fire agreement as early as Friday.

Poroshenko said he was ready to order a cease-fire in eastern Ukraine if a deal is signed at peace talks scheduled in Minsk, Belarus. The rebels seek a political settlement for their mostly Russian-speaking region.

"Look, Ukraine is fighting for peace," Poroshenko said at a news conference during the opening day of the NATO summit here. "It's Ukraine which pays the highest price every single day, losing lives of soldiers, innocent civilians." He expressed "careful optimism" about Friday's meeting.

NATO issued a statement late Thursday saying the leaders and alliance "stand united in our support of Ukraine's sovereignty and territorial integrity within its internationally recognized borders."

A day earlier, Poroshenko said he talked with Russian President Vladimir Putin about an outline toward a possible peace deal. Putin sketched out a seven-point plan that included the pullback of Ukrainian armed forces from cities and villages in the disputed eastern Ukraine regions and an end to operations by separatists.

NATO Secretary-General Anders Fogh Rasmussen remained cautious Thursday, saying, "What matters is what is happening on the ground."

Talk of a truce came as pro-Russian forces in eastern Ukraine stepped up attacks around the rebel-held city of Luhansk, and armored vehicles advanced on the port city of Mariupol, according to Ukrainian media reports.

At the two-day summit, Poroshenko met with several leaders of the 28-nation alliance, including President Obama, British Prime Minister David Cameron, French President Francois Hollande, German Chancellor Angela Merkel and Italian Prime Minister Matteo Renzi, seeking support in the months-long Ukraine crisis.

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 adviser Ben Rhodes said. "The leaders also expressed their strong support for President Poroshenko's efforts to achieve a peaceful resolution to the conflict."

In Moscow, Russian Foreign Minister Sergei Lavrov warned that Ukraine's expressed desire to join NATO is "a blatant attempt to derail all efforts at initiating a dialogue of national reconciliation."

NATO's charter says an attack on one member is an attack on the entire alliance, but the organization has made it clear that membership for Ukraine isn't in the cards anytime soon.

NATO and the United States have criticized Russia for sending weapons and troops into eastern Ukraine. Russia denies it is involved in the fighting. More than 2,600 people have died in the clashes since April, according to a United Nations report.

Obama and Cameron set the tone for the NATO gathering by penning a joint opinion piece in Thursday's (London) Times that pressed the leaders to confront the "brutal and poisonous" Islamic State militant group attacking in Iraq and Syria.

"Those who want to adopt an isolationist approach misunderstand the nature of security in the 21st century," they wrote. "Developments in other parts of the world, particularly in Iraq and Syria, threaten our security at home."

The alliance made no specific pledges of action. Rasmussen said he believed the broader international community "has an obligation to stop the Islamic State from advancing further" and would seriously consider requests for assistance, particularly from the Iraqi government.

Obama and Cameron were more blunt in their editorial: "If terrorists think we will weaken in the face of their threats, they could not be more wrong. Countries like Britain and America will not be cowed by barbaric killers."

Contributing: Oren Dorell in McLean, Va.; the Associated Press

Kim Hjelmgaard is USA TODAY's London-based deputy world editor. Follow him on Twitter:@khjelmgaard