LONDON -- The age-old link between warfare and rape can be broken, and perpetrators cannot assume that they will get away with it, actress Angelina Jolie and top diplomats said Friday as they endorsed international efforts to increase the investigation and prosecution of a crime that has historically gone unpunished.

"We refuse to believe that this is too big to defeat," Secretary of State John Kerry said, "that this is somehow too deeply ingrained in human nature or society not to care about it."

He closed a four-day conference headlined by the Hollywood actress that examined all aspects of sexual violence in wartime, including the widespread expectation that victims will not report the assault. "We are convinced that we can make a difference and that there is no place in the civilized world for sexual violence as a tool of war," Kerry said.

Diplomats, activists, lawyers, judges and victims met at the invitation of British Foreign Secretary William Hague, who has made ending sexual violence in conflict his signature cause. Individual nations pledged millions of dollars for initiatives, including outreach to improve reporting and documentation of the crime and special courts for prosecution.

"Young lives are being ruined by sexual violence in Syria, south Sudan and Central African Republic, as we gather here, as we speak," Jolie said. "For people in those countries, the actions we have promised cannot come soon enough.

For them, shattering impunity must begin now."

Earlier in the week, Hague and Jolie launched an "international protocol," a set of guidelines on collecting evidence and investigating sexual crimes. The 140-page manual includes specific proposals on, for instance, how to store forensic evidence in the aftermath of a rape.

"I am convinced that the greatest strategic prize for our century is the full social, political and economic empowerment of women everywhere, and this subject is part of that," Hague said.

Jolie and Hague joined forces two years ago after Hague saw the actress's 2011 directorial debut "In the Land of Blood and Honey," about sexual violence in 1992-1995 in the Bosnian conflict. The United Nations estimates that 20,000 to 50,000 women were raped during that war.

Rape and other forms of sexual violence are used as tools of power and intimidation against civilians around the world. Women and girls are the most frequent victims, but young men also are raped as a means to humiliate and enslave them to their abusers, activists said.

The vulnerability of women and girls in areas of conflict was highlighted by the mass abduction of hundreds of Nigerian schoolgirls in April. The same armed militia that took them is suspected in the abduction of 20 additional girls last week.

Kerry said the ancient pairing of "rape and pillage" can be undone and sexual violence no longer considered a spoil of war.