UNITED NATIONS—China’s President Xi Jinping sought to mollify concerns about his country’s growing power by pledging billions of dollars to fight poverty and gender discrimination during a United Nations meeting at the end of a weeklong U.S. visit.

The pledges appeared designed to portray China as a global leader on social issues following a U.S. presidential summit on Friday that was dominated by tensions over Beijing’s economic policies, alleged cyberattacks on the U.S., and island-building in the disputed South China Sea.

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