“We strongly condemn this criminal move,” said Abdalmahmood Abdalhaleem, the Sudanese ambassador to the United Nations, adding that the government would no longer work with aid groups it deemed hostile. “It amounts to an attempt at regime change. We are not going to be bound by it.”

But many human rights groups and Darfur exiles saluted the judges’ decision. Niemat Ahmadi, of the Save Darfur Coalition, called the warrant a lifeline for those living in camps. “It will change the mood of frustration and helplessness for our people,” Ms. Ahmadi said.

Richard Dicker, a director of Human Rights Watch, said the warrant was likely to isolate Mr. Bashir internationally. “This means he will be a fugitive, a man on a wanted poster,” he said.

In their statement, the judges called for the cooperation of all countries  not just the 108 that are members of the court  to bring Mr. Bashir to justice.

Legally, Sudan is obliged to arrest Mr. Bashir, but that seems unlikely. The court has no police force or military, and the United Nations peacekeepers in Sudan have no mandate to detain war-crimes suspects.

Beyond that, Mr. Abdalhaleem said, there is little chance that the president will be arrested in a friendly country, because many African and Arab states have rejected the prosecution of Mr. Bashir as counterproductive to peace efforts.

The question of genocide has also been divisive, but the judges said 2 to 1 that the prosecutor had not provided sufficient evidence of the president’s specific intent to “destroy, in whole or in part, a national, ethnical, racial or religious group,” the most crucial issue in determining genocide.