Two Croatian ex-generals are flying to the UN war crimes tribunal in The Hague to face charges that they took part in atrocities against Serbs in 1995.
The generals led a government offensive against ethnic Serbs
Mladen Markac and Ivan Cermak - who voluntarily boarded an Amsterdam-bound flight in Zagreb - deny any wrongdoing.
Both retired generals were indicted last week, but the Croatian government kept the warrant secret until the
suspects were informed.
The generals' surrender marks the first act of compliance with the UN court since a new government took office in December.
Co-operation with The Hague is a key condition for Zagreb's bid to start European Union entry talks next year.
Another key Croatian suspect, General Ante Gotovina, is still on the run. He is accused of the murder and disappearance of hundreds of Serbs between 1991 and 1995.
The indictment charged Mr Cermak and Mr Markac with seven counts of crimes against civilians, including persecution, murder, plundering and wanton destruction of property.
Another ex-general, Ante Gotovina, remains on the wanted list
"The generals received the indictments and expressed readiness to appear before the tribunal as soon as
possible," Croatian Justice Minister Vesna Skare-Ozbolt said earlier this week.
Rebel Serbs took up arms to oppose Croatia's secession from the old Yugoslav federation in 1991, seizing a third of the country's territory. Government troops recaptured the lands in a blitz offensive four years later.
General Cermak, 54, a wealthy oil businessman, ran the former rebel stronghold of Knin after its capture.
General Markac, 48, commanded special police units that combed the area.
Both men voluntarily underwent interrogation by tribunal investigators over the past few years.
"I was terrified of myself after I read the indictment," Mr Cermak said upon being served with the document.
"I feel it is my duty to prove that I am innocent and that the charge is absurd and unjust," he added.
Croatia has previously been reluctant to surrender its officers to for trial, fearing a popular backlash at home from war veterans.
"The Croatian government is convinced of their innocence and will provide all the legal, technical and other means for their defence," Ms Skare-Ozbolt added.
About 200 people gave the generals an emotional farewell at Zagreb airport, culminating in a rendition of the national anthem.