Former Secretary of Defense James Mattis, once one of Trump’s most well-respected advisors, has emerged from the shadows to call into question President Trump’s global leadership.

According to Fox News:

Former Defense Secretary Jim Mattis took several implicit swipes at President Trump’s leadership in an op-ed published Wednesday, warning about the fallout from fractured alliances and increasing divisiveness under the current administration.

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“Nations with allies thrive, and those without them wither. Alone, America cannot protect our people and our economy,” Mattis wrote. “At this time, we can see storm clouds gathering.”

He pointedly added: “A polemicist’s role is not sufficient for a leader. A leader must display strategic acumen that incorporates respect for those nations that have stood with us when trouble loomed.”

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“When my concrete solutions and strategic advice, especially keeping faith with our allies, no longer resonated, it was time to resign, despite the limitless joy I felt serving alongside our troops in defense of our Constitution,” Mattis wrote.

Mattis did make clear that the biggest threat to America is not from our enemies but from our internal divisiveness.