The EU has said the arrest of leading Croatian war crimes suspect Gen Ante Gotovina has cleared a major obstacle to Croatia joining the EU.
Posters with Christmas greetings from Gen Gotovina have appeared
Enlargement Commissioner Olli Rehn told the BBC that it was an important turning point for the whole region.
The EU put off Croatian entry talks in March until more was done to find Gen Gotovina. Talks began only in October.
After his arrest in the Canary Islands, he is being held in Spain awaiting transfer to the Hague tribunal.
The 50-year-old general faces persecution and war crimes charges stemming from a 1995 offensive to chase Serbs from their self-declared republic in Croatia.
His supporters have staged small protests in Zagreb and other cities.
The chief prosecutor at The Hague, Carla del Ponte, says Gen Gotovina's arrest will add pressure on Serbia to deliver the only two men above him on the wanted list - former Bosnian Serb leaders Radovan Karadzic and Ratko Mladic.
"I still do not have what they have promised to give me... I am still angry because Karadzic and Mladic are still at large, and that is a real scandal," she said.
Ms del Ponte has set a deadline of 14 December for their arrest.
In Brussels, Mr Rehn described the arrest of Gen Gotovina as crucial, although Zagreb still had work to do before it could join the EU.
"A major obstacle is cleared from the way of Croatia. There are of course other, say, normal conditions which Croatia has to fulfil such as reforming its judiciary," he told BBC Radio 4's Today programme.
"But at the same time this indeed is a very important turning point and also for the whole region, because it turns the page from the nationalist past to a European future."
Croatian Prime Minister Ivo Sanader said the arrest proved Croatia was right when it said Gen Gotovina had fled abroad.
Gen Gotovina's lawyer said his client had denied responsibility in the past and would probably plead not guilty to the charges.
The retired general was arrested in a hotel restaurant on the island of Tenerife on Wednesday night, the Spanish interior ministry said.
SUSPECTS STILL WANTED
Radovan Karadzic: Former Bosnian Serb leader regarded as the mastermind of the Bosnian war 1992-95. Accused of ethnic cleansing including Srebrenica massacre
Ratko Mladic: Bosnian Serb army commander charged with carrying out the Srebrenica massacre
Zdravko Tolimir: Worked under Ratko Mladic, accused of involvement with Srebrenica
Goran Hadzic: Self-proclaimed Serb president of the breakaway Croat republic of Krajina
Stojan Zupljanin Bosnian Serb commander accused of war crimes around Banja Luka, Bosnia
He was said to be in possession of a false Croatian passport with an assumed name.
It was unclear when he would leave for the UN court in the Netherlands.
Gen Gotovina was indicted for crimes against humanity by the war crimes tribunal in 2001.
He is alleged to have failed to prevent the murder of 150 Serbs killed by shooting, stabbing or burning during Operation Storm, the August 1995 push against Serb forces in Croatia's Krajina region.
The indictment also accuses him of co-ordinating a campaign of plunder and looting throughout operations in ethnically Serb areas of the region.