BRUSSELS — Accusing Russia of waging a campaign of “military aggression and terror” against his country, President Petro Poroshenko of Ukraine told European leaders here Saturday that their own countries’ security depended on stopping Russian troops from stoking a conflict in eastern Ukraine that he said could escalate into a wider war.
His warnings won no pledges of military assistance from the European Union, but helped set the stage for a possible new round of economic sanctions against Russia.
The European Union said it will give Russia a one-week ultimatum to scale back its intervention in Ukraine or face additional sanctions, the Associated Press reported.
EU summit chairman Herman Van Rompuy said early Sunday that the bloc’s 28 leaders ordered its executive body to ‘‘urgently undertake preparatory work for consideration within a week.’’ He said ‘‘everybody is fully aware that we have to act quickly.’’
In apparent fear of an economic backlash, EU leaders stopped short of imposing the sanctions immediately. Russia is the EU’s No. 3 trading partner and one of its biggest oil and gas suppliers.
Saying that Russia was pushing the conflict in Ukraine toward “the point of no return,” the president of the EU’s executive arm, José Manuel Barroso, said European leaders in Brussels were determined to make Moscow “come to reason.”
Some European leaders, particularly those from former Communist nations in Eastern Europe, called for direct military assistance to Ukraine’s badly stretched armed forces, which are battling pro-Russia rebels on three fronts in eastern Ukraine. But officials said a decision on military aid would be left to individual countries.
Ukraine’s military said Saturday that Russian tanks had entered and flattened a small town between the rebel-held city of Luhansk and the Russian border.
Ukraine also accused Russia of helping to shoot down one of its combat aircraft during fighting with the separatist forces in eastern Ukraine. A statement by the Ukrainian government on the Facebook page for its military operations in the southeast said the Su-25 fighter was shot down Friday, with the pilot ejecting safely. A missile from a Russian launcher struck the plane, it said.
President François Hollande of France backed new measures against Russia, telling journalists in Brussels that “what is happening in Ukraine is so serious” that European leaders were “obliged to act by increasing the level of sanctions.”
But France is expected to block calls by some leaders to extend an existing ban on future military sales to Russia to include already signed contracts.
Poroshenko, alongside Barroso in Brussels, said that Ukraine still hoped for a political settlement with the rebels but that a flow of Russian troops and armored vehicles into Ukraine in recent days to support them were setting off a broader conflict.
“We are too close to a border where there will be no return to the peace plan,” Poroshenko said, asserting that since Wednesday, “thousands of foreign troops and hundreds of foreign tanks are now on the territory of Ukraine, with a very high risk not only for the peace and stability of Ukraine but for the peace and stability of the whole of Europe.”
He added that this made Europe’s solidarity with Ukraine “crucially important for all of us.”
European leaders will instruct the European Commission, the union’s executive branch, to prepare the legal and other work needed for further restrictions on Russia’s economic and financial relations with the union’s 28 member states.
Saturday’s meeting of European leaders was originally called to discuss appointments to senior jobs, but the crisis in Ukraine overshadowed the elaborate horse trading for positions among the members.
Leaders on Saturday evening named Prime Minister Donald Tusk of Poland to replace Herman Van Rompuy as the president of the European Council, which sets the agenda for summits and helps represent the union at international gatherings.
Russia has dismayed European leaders by repeatedly denying that it has sent troops or military hardware into Ukraine. After Ukrainian officials released videos Tuesday of captured Russian troops, Moscow conceded that some of its soldiers had crossed the border but said they had done so “by accident.”
Rebel leaders say Russian troops are fighting in Ukraine during their holiday leave from the Russian army.