Unmanned U.S. drone aircraft photographed Serb troop positions and weapons emplacements and transmitted them to the Pentagon and to Gotovina’s headquarters. On one occasion, U.S.-provided intelligence enabled Gotovina to block a Serb counterthrust by massing his own troops.

The CIA also helped Croatians set up listening posts to intercept telephone calls in Bosnia and Serbia, which the Croatians shared with the National Security Agency in Washington, Croatian officials said.

When reporters arrived in Knin, the capital of Serb-held Krajina, on Aug. 7, 1995, the town was deserted because the Serbs had fled. Food was on the tables of many homes, and laundry on the lines. But contrary to the assertions of U.N. officials at the time, the shelling of the town had been limited and damaged relatively few houses. Those Serbs who remained behind acknowledged that Serb political leaders had organized a voluntary evacuation of the town to Serbia proper.

When Hague prosecutor Carla del Ponte charged that there had been an orchestrated campaign to drive Serbs from the region, diplomats and reporters were surprised because it failed to take account of the facts that had been reported on the ground and seemed geared mainly to offset the impression that the tribunal was indicting only Serbs.

Gotovina went into hiding, but Markac, who had commanded police units during Operation Storm, agreed to surrender voluntarily. Both men were sentenced in April 2011.

In Friday’s judgment, the appeals court said the lower court had established an “arbitrary rule” that if shells landed more than 200 meters from a military target, they were not directed at “legitimate military objectives” but at civilians.

Gotovina contended that the prosecutor had “failed to introduce evidence of civilian casualties or damage to civilian infrastructure” in the four main towns of Krajina – Knin, Benkovac, Obravac and Gracac – and contended that the judgment of a 200-meter margin of error for artillery firing from up to 16 miles away was not based on any established international standard.

“Absent a finding that unlawful artillery attacks took place, it is not possible to uphold the Trial Chamber’s findings regarding the JCE,” his lawyers argued, referring to the charge of a “joint criminal enterprise.”

The appeals panel in essence agreed. It said there was insufficient evidence of a policy to expel ethnic Serbs or to prevent them from returning, and that the entire verdict of a large-scale deportation of Serbs was based on the existence of unlawful artillery attacks.

“Absent the finding of unlawful artillery attacks and resulting displacement, the Trial Chamber’s conclusion that the common purpose crimes of deportation, forcible transfer and related persecution took place cannot be sustained.”

And it said that “no reasonable trial chamber could conclude that the only reasonable interpretation of the circumstantial evidence on the record was the existence of a JCE with the common purpose of permanently removing the Serb civilian population from the Krajina by force or threat of force.”