UNITED NATIONS -- The United States ambassador to the U.N., during a emotional ceremony here marking the 1994 Rwandan genocide, said that the U.S. government had failed to prevent the mass killings that began 15 years ago on Tuesday.

"Rwanda did not suffer from 'ancient hatreds' between Hutu killers and Tutsi victims," Ambassador Susan Rice said. "It suffered from modern demagogues, from ... those who were willing to kill in the warped name of ethnic difference, from those who saw division and death as a path to power."...

On the National Security Council at the White House at the time of the genocide, Ms. Rice's position was director for International Organizations and Peacekeeping. In 1997, she got a brief on Africa at State as assistant secretary for African Affairs. She said she visited Rwanda in December 1994, six months after the genocide ended.

"I'll never forget the horror of walking through a churchyard and schoolyard where one of the massacres had occurred. ... The decomposing bodies of those who had been so cruelly murdered still lay strewn around what should have been a place of peace," Ms. Rice said.

In 1998, President Bill Clinton traveled to Rwanda and apologized for Washington's failure to act.