Former Defense Secretary Bob Gates savaged Donald Trump in a Wall Street Journal op-ed published Saturday, declaring the Republican presidential nominee “unqualified and unfit to be commander-in-chief.”

“At least on national security, I believe Mr. Trump is beyond repair,” Gates wrote. “He is stubbornly uninformed about the world and how to lead our country and government, and temperamentally unsuited to lead our men and women in uniform.”

He offered some gentle criticism of Democratic presidential nominee Hillary Clinton, urging her to be more candid on how she’d deal with China, Russia, North Korea, and Iran. He also suggested she suffers from “credibility issues” on national security and transparency, but he argued she “has time before the election to address forthrightly her trustworthiness, to reassure people about her judgment.”

Gates, now the chancellor at William & Mary, offered no such optimism on Trump, describing the GOP nominee as “naïve and irresponsible” on Russia, “oblivious” on the fight against ISIS, and “willfully ignorant” about foreign relations and the military.

“The world we confront is too perilous and too complex to have as president a man who believes he, and he alone, has all the answers and has no need to listen to anyone,” Gates wrote. “In domestic affairs, there are many checks on what a president can do; in national security there are few constraints. A thin-skinned, temperamental, shoot-from-the-hip and lip, uninformed commander-in-chief is too great a risk for America.”

Gates stressed the importance of having a president whose advisors will say what needs to be said, not necessarily what the president wants to hear – a theme he also expressed during a May interview with “Face the Nation” moderator John Dickerson.

“I worked for some very different presidents,” Gates, who has served in eight different administrations, said in May. “Each one of those presidents, as strong-minded as each of them was, understood he did not have all the answers, and surrounded himself with experienced, thoughtful people who would give good advice, and they were willing to listen. They would often make their own independent judgments. They often would act contrary to the advice they were receiving. But, nonetheless, they only acted after they had listened to different points of view and then had the opportunity to make up their mind.”

Trump, Gates said, “seems to think that he has all the answers and that he doesn’t need any advice from staff or anybody else, and that he knows more about these things than anybody else, and doesn’t really feel the need to surround himself with informed advisers.”

Notably, in a CBS News Battleground Tracker poll of likely voters in swing states released Sunday, 23 percent of Trump supporters said the GOP nominee should follow his instincts on foreign policy, rather than listening to advisors. Only 12 percent of Clinton supporters said the same.