Ukraine's President has declared a national day of mourning following the attack on a military plane which ended with 49 people dead.
Petro Poroshenko has vowed that the pro-Russian separatists responsible for the attack will be "punished".
He also hinted at sanctions against his own security officials for apparently failing to provide adequate protection for the aircraft and ordered a ""a detailed analysis of the reasons" the attack was allowed to take place.
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The announcement came a day after a famine was declared in two areas of South Sudan following three years of civil war and severe inflation.
It is unclear what their alleged plans were.
Anti-terror police are currently questioning the men who were arrested at three separate locations in France.