Facebook founder Mark Zuckerberg used his opening speech at his company's annual conference to speak out against those calling for a "wall," for "slowing immigration," and for "reducing trade." Zuckerberg's comments appeared directly aimed at the Republican frontrunner, Donald Trump.

"We stand for connecting every person. For a global community. For bringing people together. For giving all people a voice. For a free flow of ideas and culture accross nations," said Zuckerberg. "And this idea of connecting the world has gotten stronger over the last century."

Added the Facebook founder, "But now as I look around and as I travel around the world, I'm starting to see people and nations turning inward. Against this idea of a connected world and global community. I hear fearful voices calling for building walls and distancing people they label as 'others,' for blocking free expression, for slowing immigration, for reducing trade ... It takes courage to choose hope over fear."

The tech mogul tried to be optimistic. "Instead of building walls, we can help people build bridges. And instead of dividing people, we can bring people together. We do that one connection at a time. One innovation at a time."

"That's why I think the work we're doing together is more important now than ever before," said Zuckerberg.