Ukraine’s increasingly bloody conflict went on hold Friday, after the government and pro-Russian rebels signed a cease-fire deal that at least temporarily solidified the insurgents’ territorial gains.

The agreement, made with the Kremlin’s endorsement, appeared to be a first step toward the type of dormant conflict that Russia has exploited to exert control over former satellites in the decades since the Soviet Union’s collapse, including thwarting their chances of joining the NATO defense alliance.

With rebels making swift gains across eastern Ukraine this week, and preparing to seize the key industrial port city of Mariupol, it seemed that Ukrainian authorities felt they had little choice but to push for a halt to hostilities. The rebels turned the tide of battle early last week after receiving heavy backing from Russian ­forces, Kiev and its Western allies say. The Kremlin denies aiding the rebels.

The cease-fire deal was made as leaders of NATO countries gathered in Wales this week for discussions focused on the conflict. The terms of the deal underscored Russia’s apparent willingness to commit far more resources than the West to achieve its aims in Ukraine. Kiev has asked for Western military aid, but relatively little has been forthcoming, in part because of Western caution about getting pulled into a proxy military conflict with Russia inside a non-NATO-member nation.

In Wales, Ukrainian President Petro Poroshenko told reporters that he welcomed the deal, and he offered political concessions to the eastern regions that would significantly increase their autonomy and would guarantee their ability to use the Russian language, key demands when the fighting started in mid-April.

“We are really doing our best to keep peace and stability in the eastern part of Ukraine,” Poro­shenko said. “This is a very important challenge, not only for Ukraine, not only for the region. For the whole world.”

Poroshenko said he was satisfied that the deal respects Ukraine’s sovereignty and territorial integrity. He said the terms were based on a conversation he and Russian President Vladimir Putin had earlier this week.

Although leaders ranging from Poroshenko to President Obama voiced skepticism about how long the break in hostilities could hold, fighting mostly quieted in eastern Ukraine on Friday evening as both sides for now lay down arms, witnesses said.

Envoys in Minsk, Belarus, said that they planned to swap all the prisoners they had taken beginning as early as Saturday, freeing more than 1,000 people on each side.

As part of the deal, heavy weaponry is also supposed to be pulled back from the combat zone and humanitarian corridors will be set up to facilitate international aid deliveries. The full text of the 12-point agreement was not immediately released, and the envoys, which included representatives from Ukraine, Russia, the rebels and the Organization for Security and Cooperation in Europe, said they would continue discussions next week.

But with rebel leaders saying in Minsk that they still desired full independence from the rest of Ukraine, it remained unclear how long the cease-fire could hold.

The deal “does not mean that the path for secession will change somehow,” a rebel leader, Igor Plotnitsky, told reporters in Minsk, in remarks that were broadcast on Russian state television.

This map shows the latest available front lines in Ukraine.

Any deal that gives major concessions to the rebels is already bitter tonic to the pro-Kiev supporters of Ukraine’s current leadership. Losing Ukraine’s eastern industrial heartland would probably spark renewed protests in Kiev, more than six months after pro-European demonstrations toppled President Viktor Yanu­kovych. That unleashed first Russia’s annexation of the Crimean Peninsula and then the violence in the east.

Offering a glimpse of divisions within the Ukrainian government, Prime Minister Arseniy Yatsenyuk said Friday that any peace plan dictated by Putin would be unacceptable. What Ukraine needs, he said, is for all foreign troops to leave Ukrainian soil and for strong border defenses to be erected, Interfax reported.

Russian analysts have said that the Kremlin wants eastern Ukraine to have enough political power that regional leaders would be able to veto any move by Ukraine to join NATO, which the Kremlin says is a major threat to Russian security.

In a news conference at the close of the NATO summit, Obama said the 28-member alliance was “fully united in support of Ukraine’s sovereignty, independence and territorial integrity and right to defend itself.” H1e said all 28 have agreed to provide security assistance to Ukraine, including non­lethal support as well as help to modernize the Ukrainian armed forces.

In an indication of how little faith the West places in the cease-fire, Obama said the United States and the European Union would move ahead with an escalation of sanctions against the Russian energy, defense and finance sectors — a position echoed by European leaders, including British Prime Minister David Cameron.

Obama said the sanctions could be rolled back if the cease-fire holds. But he suggested that it was more likely that Russia would continue its intervention and that the West’s efforts to isolate Russia would intensify.

As expected, NATO leaders meeting in Wales formally approved the creation of a joint rapid-reaction force that could respond to military crises within two to six days — far faster than under current NATO arrangements. The alliance’s outgoing secretary general, Anders Fogh Rasmussen, said most details about the makeup of the force and its home base would be determined later.

NATO has said that several thousand Russian soldiers are on Ukrainian territory, a charge the Kremlin denies.

But amid growing worry among military families in Russia that many soldiers have suddenly cut off contact and stopped answering cellphone calls in recent weeks, Russian state television this week for the first time broadcast footage of the funerals of Russian servicemen killed in Ukraine. The soldiers had gone on vacation immediately before going to Ukraine as volunteers, the report said, and had not informed their superiors.

The violence has claimed the lives of 846 Ukrainian soldiers, a military spokesman said, including seven in the past day.

In another development, Estonian leaders said Friday that a counter­intelligence officer had been abducted at gunpoint into Russia, just two days after Obama visited their country and vowed that NATO would protect them from any attack.

Details about the incident were still unclear, but Estonian President Toomas Hendrik Ilves described it as a kidnapping on Estonian soil.

Gowen reported from Kiev. Griff Witte, Katie Zezima and Craig Whitlock in Newport, Wales; William Branigin in Washington; Karoun Demirjian in Moscow; Daniela Deane in Rome; and Natalie Gryvnyak in Kiev contributed to this report.