WASHINGTON - President Donald Trump said Monday that negotiations over U.S. troop withdrawals from Afghanistan are dead, two days after he called off a secret meeting at Camp David with Afghan and Taliban leaders to secure a deal.

"They're dead," Trump told reporters outside the White House, referring to the negotiations. "They're dead. As far as I'm concerned, they're dead."

The chief envoy to the talks, Zalmay Khalilzad, said last week that an agreement "in principle" had been reached, under which the United States would partially withdraw its troops from Afghanistan in exchange for the Taliban renouncing al-Qaida, which had orchestrated the 2001 attacks.

U.S. officials expected the tentative agreement to advance a comprehensive cease-fire and talks between the Taliban and the Afghan government. But after attacks and bombings by the Taliban, including one that killed a U.S. soldier, further talks over ending the 18-year conflict began to waver.

Trump abruptly announced on Twitter Saturday night that he had "called off peace negotiations" after the Taliban took responsibility for the attack.

"What kind of people would kill so many in order to seemingly strengthen their bargaining position?" Trump tweeted. "They didn't, they only made it worse!"

Lawmakers on both sides of the aisle sharply criticized Trump over the weekend for inviting Taliban leadership to Camp David.

On Monday, Trump defended his invitation, arguing that wars would "go on forever" without meetings.

"I took my own advice. I liked the idea of meeting. I've met with a lot of bad people and a lot of good people" since becoming president, he said.

Having the meeting at the White House would have been "a step too far," he added. "And I thought Camp David would be good, and I still do."

The president also pushed back against a report that Vice President Pence and national security adviser John Bolton had urged him to call off the meeting.

"We had a meeting scheduled," Trump said. "It was my idea. And it was my idea to terminate it."

Shortly before Trump addressed reporters, Pence echoed the president's claim that the report was "fake news" in a tweet that bore many similarities to Trump's style.

"That's Absolutely Right Mr. President," Pence tweeted. "More Fake News! The Dishonest Media never contacted our office before running with this story and if they had, we would have told them I FULLY support your decision."

NBC News, the outlet that broke the story, had reported Sunday that Pence's office and a Trump spokesman did not immediately respond to its requests for comment.

In a statement late Monday afternoon, Darin Miller, a spokesman for Pence, also pushed back against the notion of infighting within Trump's administration over Afghanistan.

"The Vice President reserves his counsel for the President, and anyone claiming to know his thoughts on the matter aside from the President is mistaken," he said.

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The Washington Post's Karen DeYoung and Ashley Parker contributed to this report.

This article was written by Felicia Sonmez, a reporter for The Washington Post.