At European Meeting on Partnership, Ukraine and Armenia Balk President Viktor F. Yanukovich of Ukraine, right, arrived to a chilly reception Thursday at a meeting in Vilnius, Lithuania. VILNIUS, Lithuania - A European summit meeting that opened here on Thursday was supposed to celebrate the achievements that put former Soviet republics on a path to Western integration - a program that would ultimately fulfill the more than half-century pursuit of a truly Continental economic and political alliance. Instead, two of the former republics, Ukraine and Armenia, have balked at closer ties with Europe under pressure from Russia, leaving European leaders gathered in this Baltic capital struggling to explain how their plans came apart, and turning the event here partly into a strategy session over how to confront the unexpectedly strong challenge from Moscow. While leaders, including the German chancellor, Angela Merkel, portrayed the setbacks as temporary, they conceded that the most important signing ceremony they had planned - of political and trade accords with Ukraine - would not take place on Friday or anytime soon. "I have no hope that it will succeed this time," Ms. Merkel said, arriving at the talks here. But the door is open. At a working dinner at the ornate Palace of the Grand Dukes, over plates of sturgeon with celery mousse and venison with apple purée, leaders tried to remain upbeat, highlighting in speeches the remarkable transformation of Europe in recent decades. "That's the whole point of Europe, that we don't have to create camps and fight with each other, but to create common spaces," said President Giorgi Margvelashvili of Georgia, whose country, along with Moldova, emerged as a hero of the gathering by moving forward with its own preliminary agreement with the European Union. Yet attention still focused on President Viktor F. Yanukovich of Ukraine, whose decision last week to scrap plans for signing the accords and call instead for negotiations with Russia and Europe set off protests in Kiev, the capital, and other cities. Those demonstrations continued Thursday as Mr. Yanukovich arrived here to a chilly reception. The dispute over Ukraine's future adds yet another flash point to a tense relationship between officials in Moscow and Brussels. Several officials and experts said that Western governments, including the United States, badly underestimated Russian opposition to the expansion of European economic and political influence. While Europe promised mostly esoteric benefits, they said, Russia leveled concrete threats - involving the economy, in the case of Ukraine, and security, in the case of Armenia. "Russia did a much better job of explaining pocketbook issues in a very forceful way than Europe did in explaining abstract political benefits," said Bruce Jackson, the president of the Project on Transitional Democracies, an American nonprofit group that has concentrated on Eastern Europe. "Russia wanted this more than we did, certainly more than America did; we didn't even show up," Mr. Jackson said. That criticism was echoed by Arseniy P. Yatsenyuk, who leads the largest opposition coalition in the Ukrainian Parliament. In an interview on Thursday, Mr. Yatsenyuk said that he had been warning the West for months that Mr. Yanukovich could not be trusted to sign the accords. "I was a little bit astonished when our Western partners really trusted this president," Mr. Yatsenyuk said outside the Merchant's Club in Vilnius. "I was talking to everyone in Brussels and Washington, saying, "Guys, wake up!" " Among the questions being pondered by European leaders trying to figure out what went wrong was whether they had put too much energy and effort into the case of the jailed former prime minister of Ukraine, Yulia V. Tymoshenko. Western leaders have long criticized her conviction and seven-year prison sentence on abuse of authority charges as politically motivated and had insisted on her release as a precondition to signing the accords. In a sign of how central Ms. Tymoshenko's case had become to the integration discussions, her daughter, Evgenia, spent much of Thursday speaking to reporters in the lobby of a hotel in the Old Town of Vilnius, where some European leaders were meeting. She said her mother's case was emblematic of Ukraine's deeply troubled judicial system, which European leaders have said must be overhauled. Still, Evgenia Tymoshenko said her mother had urged European leaders to move forward if Mr. Yanukovich was willing to sign the accords, even if he refused to release her. Officials here were also left questioning whether they should have moved more aggressively to address Ukraine's serious economic problems and need for a major financial aid package. The country has been in talks with the International Monetary Fund for months, but it is not clear that officials regarded the situation with urgency until it was too late. Some officials said Mr. Yanukovich was caught between Russia and Europe, hoping for help but with none immediately forthcoming from either side. And in Ukraine, some supporters of European integration are joking darkly that their country has been left "with the politics of Russia and the economy of Greece." "President Yanukovich is now putting his country in a situation that is extremely vulnerable to pressure," said Carl Bildt, the Swedish foreign minister. He has lost the opportunity to anchor to Europe, and he is drifting. I don't know which direction he is drifting - east or down.