Participating countries said the exercise increases regional co-operation and supports regional security.
The trial could be one of the most important in Greece's recent history, analysts say.
Following the crash of a MiG-21 fighter jet, Croatia debates if it should partner with another nation as part of NATO's Smart Defence programme, or reinvest in its military.
Citizens and experts urge states to react decisively against ISIL and its propaganda.
Regional countries try to avoid confusion over Russia's attempt to create a new flight region including Crimea and parts of Ukraine.
Better exchange of information will bring closure, according to bloggers.
More than 40 people were arrested in a large operation across Kosovo for recruiting fighters for ISIL and al-Nusra.
The Serbian War Crimes Prosecution ordered an investigation of the military general Dragan Zivanovic, the first general suspected by the Serbian judiciary of command responsibility for war crimes in Kosovo.
Albania announced the first visit by its head of government to Serbia in over half a century.
Armies in the region have been improving their co-operation through joint military medicine activities.
Such images go against the human feelings of everyone, except for the extremists, a Kosovo analyst said.
Indictments by an EU task force are expected to be filed once a special court is established next year.
The president seeks greater institutional co-operation to reduce religious hate speech and vandalism.
NATO's top general said that nations in the alliance are co-operating to combat extremism.
Military exercises brought allies and partners together to deepen strategic co-operation.