A retired Naval pilot who worked as the speechwriter for former Defense Secretary Jim Mattis said Tuesday that America is less safe under the Trump administration — and its reputation is tattered around the world.

"I think that America is not only less safe, but I also worry that our international standing has been eroded and it's going to take years to rebuild that," Guy Snodgrass said on CBSN's "Red & Blue."

Snodgrass pointed to several of President Trump's defense decisions that Mattis would not support. That includes the recent withdrawal of U.S. troops from northern Syria, which abandoned America's Kurdish allies in the region.

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Snodgrass said he thinks Mattis would still disagree with the withdrawal, even after the recent U.S. raid in Syria that led to the death of ISIS leader Abu Bakr al-Baghdadi.

Mattis "would say that America gives its word and should keep it," Snodgrass said.

Guy Snodgrass on CBSN's "Red & Blue" CBS News

He added that Mr. Trump is so interested in "pinning medals on its own chest" that he's willing to undermine the legacy of former President Barack Obama, as well as America's long-standing alliances.

"The danger is that, after being partnered up with other nations for decades, to suddenly undo that on a whim is something that does not serve well in the long term," Snodgrass said.

This week, Snodgrass released "Holding the Line: Inside Trump's Pentagon with Secretary Mattis," a book about his time working with the Trump administration. The book details the clashes between Mr. Trump and Mattis, who announced his resignation as defense secretary in December 2018.

Snodgrass took the Pentagon to court after it held up the book for months. He said even Mattis himself asked him not to write it.

"Holding The Line" came out just weeks after the release of Mattis' own book, "Call Sign Chaos: Learning to Lead," which he wrote with Bing West. Mattis' book is more tight-lipped about his tumultuous times with Mr. Trump, focusing instead on Mattis' decades of service in the Marine Corps. But Mattis does take some swipes at Mr. Trump, writing, "I did as well as I could for as long as I could."

Meanwhile, Snodgrass' book details numerous instances of Mattis and his staff being thrown off by the president's decisions. There's a chapter called "Summer of Surprises" that discusses Pentagon officials allegedly getting caught off-guard by Mr. Trump creating a Space Force and attacking NATO allies to pay more for defense. Officials sometimes learned about decisions on Twitter, the book added, and had to field "frantic" phone calls from allied nations who didn't understand what those moves meant.

"There were a number of times where this administration would catch us at the Pentagon flat-footed," Snodgrass said on "Red & Blue."

He added that Mr. Trump's alleged failure to loop in the Pentagon on these decisions was "like pulling out your pistol and shooting yourself in the foot."