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President Barack Obama called Gold Star families “the very best of our country” on Monday after 23 families of fallen service members slammed Trump for critiquing the parents of a Muslim soldier killed in Iraq.

“Our Gold Star families have made a sacrifice that most of us cannot even begin to imagine,” Obama said while addressing a conference of disabled veterans. “They represent the very best of our country…We have to do everything we can for those families and honor them, and be humbled by them.”

The letter from Gold Star families came amidst Trump’s escalating feud with Khizr and Ghazala Khan, whose son was killed by a car bomb in Iraq in 2004. Trump questioned why Ghazala Khan did not speak at last week’s Democratic convention and then fired off tweets to rebut Khizr Khan.

The president also took an indirect shot at the GOP nominee for routinely asserting that Obama has weakened the U.S. military

“As commander in chief, I’m pretty tired of some folks trash talking America’s military and troops,” Obama said.