President Barack Obama says atrocities against peoples across the globe begin with daily ignorance and intolerance and that the world must not allow such "seeds of hate" to take root again.
Obama spoke at the U.S. Holocaust Memorial Museum, his first such appearance as president. He was announcing a plan to impose sanctions against foreign entities, chiefly Iran and Syria, who use technology to crackdown on dissidents.
Obama broadly defended his government's steps to halt masskillings during his three-plus years in office.
He said "we have saved countless lives."
In a warning to other nations, the president said that national sovereignty is never a license to "slaughter your people."