Faced with pressure from Russia, Ukraine's leaders last week shelved plans for further integration with the EU, sparking massive protests at home setting back EU plans to pry a nation of 46 million people loose from Moscow's orbit.
Russia would like Kiev to join a separate union that aims to rival the EU.
The association agreement with Ukraine, with its provisions for closer trade ties, was supposed to be the signature event of the two-day summit in this former Soviet republic — now an EU member — and a clear indication the EU was pushing its geopolitical clout ever more eastward, right up to the Russian border.
Instead, the formal initialing of similar agreements with another two former Soviet republics, Georgia and Moldova, with populations of 4.5 million and 3.6 million respectively, will have to do as a possible summit highlight.
Pat Cox, the former European Parliament president who is now leading an EU monitoring mission in Ukraine, said that "Ukraine, as a sovereign state, is entitled to say 'yes,' 'no' or 'maybe' — and it seems to be 'maybe' at the moment."
Ukraine's first deputy prime minister, Serhiy Arbuzov, indicated that the suspension of the signature of a far-reaching association agreement was not final.
"My presence here means that we continue to work, are ready to meet and look for solutions," Arbuzov, a staunch ally of Ukrainian President Viktor Yanukovych, said, according to the Interfax news agency.
"I am sure that we will find a solution," he said Thursday, adding that his country "needs Europe, a European course."
Thousands of people have kept up daily protests in Ukraine's capital against Yanukovych's decision to drop further EU integration for closer ties with Russia.
It was mass popular protests in 2004, known as the Orange Revolution, that brought down Yanukovych, and he is wary of a repeat of the same scenario now.
Analysts believe that Yanukovych is trying to play both sides, while attempting to secure a better short-term deal with Moscow.
"The Yanukovych line at Vilnius seems to be to play for time-keep options open, and come away with something which he can then use in negotiations with Russia likely next week over a gas-financing deal," said Tim Ash, chief emerging-markets economist at Standard Bank in London.
"He probably hopes he can get enough 'warm words' from EU leaders in terms of the EU integration process to calm the mood on the streets, and take momentum out of street demonstrations," Ash said.
The EU itself seems resigned to play the waiting game.
EU Enlargement Commissioner Stefan Fuele said he is "ready to resume the preparations for the signature of the association agreement as soon as Ukraine is ready."