Without naming the top two GOP candidates, Zuckerberg blasted the ideas of building a wall, keeping out immigrants, and blocking global trade. Speaking at Facebook’s F8 developer conference in San Francisco on Tuesday, Zuckerberg spent the first 10 minutes of his keynote talk addressing politics instead of programming.

“I hear fearful voices calling for building walls and distancing people they label as others, for blocking free expression, for slowing immigration, reducing trade and, in some cases around the world, even cutting access to the internet,” said Zuckerberg.

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“You have to be optimistic to think that you can change the world,” he continued.

Trump has repeatedly said that if elected, he would construct a wall along the U.S. border with Mexico and get Mexico to pay for it. Trump has also proposed imposing stiff tariffs on goods imported from China and Mexico. Both Trump and Cruz have pledged to crack down on immigration and deport people already in the United States.

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“Our lives are connected and whether we’re welcoming refugees fleeing wars or an immigrant seeking a new opportunity, whether we’re coming together to fight global disease like Ebola or to address climate change, I hope that we have the courage to see that the path forward is to bring people together, not push people apart, to connect more, not less.” Zuckerberg concluded. “We are one global community.”