Thousands of demonstrators took to the streets of Moldova on Tuesday, fighting with police and ransacking parliament.
The BBC News website looks at the causes and potential consequences of the unrest.
What sparked the violence?
Protesters have been angered by an election result they believe was rigged. The ruling Communist Party won 50% of the vote, according to official results, with the nearest opposition party taking only 13%. News of protests in the capital, Chisinau, spread via text messages and the internet, and an angry crowd of about 15,000 - according to organisers - gathered. Clashes broke out with police, and the demonstrators broke into and ransacked parliament.
Was the election rigged?
The Organisation for Security and Co-operation in Europe gave a mostly positive assessment of the poll, saying election day went smoothly, though it noted some flaws. The Communist victory was not unexpected - opinion polls before the vote gave it about 36%, while the three main opposition groups mustered only about 22% between them.
But opposition figures have made allegations of repeat voting by Communist supporters, and one OSCE observer questioned the group's "too warm" assessment. Baroness Emma Nicholson told the BBC that she and others had a "very, very strong feeling" that there had been manipulation.
Who is behind the protests?
Pro-democracy groups say the protests were a spontaneous reaction to the election result, which grew rapidly through word of mouth and messages over the internet and mobile phones. The main opposition parties say they had no major role in the protests.
But Moldova's president, and the Russians, have accused neighbouring Romania of stoking the protests. Some in Russia perceive Western governments trying to foment regime change, and draw a link with other European protest movements.
"These are provocateurs at work, using the elections as a shield. The same people stand behind the events in Moldova, the Orange Revolution in Ukraine, and behind [President Mikhail] Saakashvili in Georgia," said Gennadiy Zyuganov, the leader of Russia's Communist Party.
So is revolution in the air?
Mark Grigoryan, of the BBC's Russian Service, says the Moldovan protests do not seem to have either the level of organisation, or the development over time, of those in Georgia in 2003 or Ukraine in 2004.
He cites Moldovan analyst Vladislav Kulminskiy, who doubts the events will lead to regime change, since the Communists have genuine public support.
What are the links between Moldova and Romania?
Moldova - or Bessarabia as it was known - was unified with Romania in the early 20th Century but was annexed by the Soviet Union in World War II.
There remain close cultural links between Romania and Moldova, where Romanian is the main language spoken.
Some of those protesting on Tuesday were calling for reunion with Romania - perhaps inspired by Romania's place in the EU and the dreams of prosperity associated with it.
Moldova is the poorest country in Europe, where the average wage is just under $250 (£168) a month.
There remains an unresolved conflict with the breakaway region of Trans-Dniester, which has run its own affairs, with Moscow's support, since the end of hostilities in a brief war in 1992.