Voters in the Netherlands have rejected in a referendum an EU partnership deal to remove trade barriers with Ukraine.
Turnout was low, 32.2%, but above the 30% threshold for the vote to be valid. The deal was rejected by 61.1% of votes, compared with 38.1% in favour.
Prime Minister Mark Rutte said the government may have to reconsider the deal, although the vote is not binding.
Ukrainian President Petro Poroshenko insisted his country would "continue our movement towards the EU".
A foreign ministry official in Kiev told foreign media that the result was disappointing, adding that Dutch Eurosceptics could not take Ukraine hostage to express dissatisfaction with the EU.
The vote was widely seen in the Netherlands as a test of public opinion towards the EU.
It was triggered by an internet petition begun by Eurosceptic activists that attracted more than 400,000 signatures.
The result creates a headache for the Dutch government, as the Dutch parliament approved the EU association agreement with Ukraine last year. All the other 27 EU member states have already ratified the deal.
"My view is that if the turnout is more than 30%, with such a victory for the 'No' camp, ratification cannot go ahead without discussion," Mr Rutte said in a televised reaction. It is also an embarrassment for a Dutch government that currently holds the EU presidency.
Geert Wilders, who leads the anti-EU and anti-Islam Freedom Party, said the result was the "beginning of the end for the EU", foreign media reports.