Bosnian Serb wartime general Ratko Mladic went on trial at The Hague Wednesday, the first day in the long-awaited war crimes trial in which the defiant 70-year-old taunted the families of victims.

International prosecutors have indicted Mladic on 11 counts of war crimes and crimes against humanity, including genocide, committed during the early 1990s in the Bosnian ethnic conflicts.

Mladic entered the courtroom defiantly, with thumbs-up and clapping his hands. He ran his fingers across his throat as he looked at the victims' families watching behind bulletproof glass.

The prosecution showed video footage and transcripts of Mladic's phone conversation as evidence of his role in the killing of civilians during the 43-month-long siege of Bosnia's capital Sarajevo.

Prosecuting lawyer Dermot Groome told the U.N. court that Mladic ordered his troops to kill those who were not Serbs in the Bosnian territory he considered part of Serbia.

“He assumed a mantle of realizing, through military might, the criminal goals of ethnically cleansing much of Bosnia.''

Mladic is accused of helping orchestrate the bloody siege of the Bosnian capital, Sarajevo, and ordering the massacre of 8,000 Muslim men and boys in the UN-protected Srebrenica enclave in July 1995.

Prosecutors say they will use evidence from more than 400 witnesses, though very few of them will testify in court. The first witness is scheduled to start testifying May 29.

Mladic's lawyer Branko Lukic said the defense is asking for a delay because more time is needed to study the huge case file.

“We couldn't continue without a postponement. It is not possible to read through a few millions pages in two weeks, it's impossible. We were really conservative in asking for delays and we asked for the minimum. After the latest findings of how much time we need, we asked for six months. How much we will be given, we shall see.''

But many relatives of the victims expressed frustration at the delays, and said they hope that the ailing Mladic will survive to see justice being done.

But Mladic is considered a hero by many Serbs, especially in Bosnia. He was arrested a year ago in Serbia, after about 16 years on the run as one of Europe's most wanted men. Observers say he could not have been in hiding so long without a support network.