WASHINGTON — President Trump on Monday denounced white supremacy in the wake of twin mass shootings over the weekend, and citing the threat of “racist hate,” he summoned the nation to address what he called a link between the recent carnage and violent video games, mental illness and internet bigotry.

But he stopped well short of endorsing the kind of broad gun control measures that activists, Democrats and some Republicans have sought for years, such as tougher background checks for gun buyers and the banning of some weapons and accessories such as high-capacity magazines.

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And while he warned of “the perils of the internet and social media,” he offered no recognition of his own use of those platforms to promote his brand of divisive politics. Instead, he focused on a rising intolerance that he has been slow to condemn in the past.

“In one voice our nation must condemn racism, bigotry and white supremacy,” Mr. Trump said at the White House. “These sinister ideologies must be defeated.”