The mood in Kyiv was glum after Britain's shock decision to leave the European Union following a countrywide referendum.
The city saw deadly mass protests two years ago in defense of Ukraine's rapprochement with the European Union, and news of the Brexit vote met with dismay in the Ukrainian capital.
Officials mostly put on a brave face, voicing confidence that the EU will remain united despite Britain voting to leave the bloc.
Their statement nonetheless betrayed concerns that the Brexit could weaken Brussels' support for their country and undermine its efforts to stand up to Russia.
"We have suffered for our European choice and continue to pay a high price for it by defending not only our sovereignty but also the eastern border of Europe," said Prime Minister Volodymyr Hroysman. "Therefore, we will continue to fight for a stronger united Europe and pour new energy into the European integration process."
Ukrainian President Petro Poroshenko turned to Twitter to voice his hopes that Western sanctions against Russia will be maintained.
"Today the current challenge for the European Union is to find a way to the hearts of Euroskeptics so as not to allow a single chance to the opponents of the euro-integration project and to their generous sponsor," he wrote, in an apparent allusion to Moscow.
Many in Ukraine are also worried that the Brexit could derail the much-awaited EU visa waiver for Ukrainian citizens.
Iryna Herashchenko, parliament's deputy speaker, warned that Europe will pay a "heavy price" for what she called "the populism and the irresponsibility of politicians."
"Unfortunately, this will directly affect our country," she warned on Facebook. "Can this delay the visa-free [regime]? Yes, unfortunately."
In eastern Ukraine, news of Britain's decision drew triumphant comments from pro-Russia separatists controlling large swaths of the region.
Oleksandr Zakharchenko, the leader of separatists who hold territory in the eastern Donetsk region, congratulated Britain and said he hoped the British referendum would change Europe's attitudes toward two unrecognized separatist 'republics' in Ukraine.
"Britain did what we did two years ago: we also held a referendum, voted, and left Ukraine," he said. "Fortunately for Britain, they didn't send planes against them, they are not calling them separatists."
Britain's decision to leave the EU sent similar shock waves through neighboring Moldova.
Prime Minister Pavel Filip lamented what he described as "a sad day for Europe," but stressed that Moldova, which signed an Association Agreement with the EU in 2014, would remain committed to joining the bloc.
"The European project needs now, more than ever, to be reaffirmed and trusted," he said. "Moldova will remain attached to its EU road, despite the result in the U.K., because we trust the European Union as a successful project."
There are fears in Moldova that Britain's EU departure could lead to slashed funding for the impoverished country and affect the large Moldovan diaspora working in Britain.
The vote could also bolster support for Moldovan politicians advocating closer ties with Moscow.
Igor Dodon, the leader of the opposition Socialist Party, was quick to hail the vote. The outcome, he said, showed "the EU has only a past, not a future." Dodon is currently leading in the polls ahead of Moldova's October presidential election.
Renato Usatii, the head of the pro-Russian Partidul Nostru party, also praised Britain's vote and predicted the "unraveling" of the EU.
In Belarus, authorities remained tight-lipped about Britain's choice.
But opposition leaders voiced concerns that Britain's exit will play into the hands of the Kremlin by temporarily paralyzing Europe and depriving it of one its most virulent critics of Russian President Vladimir Putin.
"It's bad news for us," lamented Alyaksei Yanukevich, the head of the opposition Belarusian Popular Front. "Over the next few years, Britain and other European countries will be very busy taking care of their internal affairs, they will be building a new architecture for Europe, and this means that outside the EU, most particularly in our region, the Kremlin will have more leeway.
In the other three Eastern Partnership countries -- Georgia, Armenia, and Azerbaijan -- reaction to the Brexit vote was more serene.
"In terms of possible political impact to Azerbaijan, the EU didn't cooperate with us so closely, so I'm not expecting any impact on bilateral relations," said Rasim Musabeyov, a lawmaker in Azerbaijan's parliament.
Experts say the immediate fallout of the Brexit vote for Azerbaijan is mostly economic; the country's oil fund keeps 5 percent of its assets in Britain's currency -- more than 1.1 billion British pounds.
In Georgia, Prime Minister Giorgi Kvirikashvili expressed his "personal regret" at the outcome of the British referendum but said he had "no doubt" the European Union will survive the blow.
"This vote will not change the fact that the European Union is the most important and powerful regional political and economic union in the world," he said. "Its strength will continue to grow."
RFE/RL's Ukrainian, Belarusian, Moldovan, Azerbaijani, and Georgian services contributed to this report.