One of America's most respected former military officials is worried about the 2016 presidential field
"Could you imagine a President Donald Trump?" he was asked.
"In all honesty, that's difficult for me," he told Business Insider in an interview earlier this week.
In fact, the entire 2016 presidential field seems to be confounding Gates, one of the most-respected military officials in modern US history.
Gates served as the US secretary of defense under Presidents George W. Bush and Barack Obama, and is the only person to have held that position under two presidents of two different political parties.
Yet just more than a week before the first votes are cast in the presidential primaries, none of the current crop of candidates, Gates told Business Insider, stands out as especially presidential.
Hillary Clinton, the Democratic front-runner with whom he worked in the Obama administration, does not have his endorsement. Some of Trump's rhetoric is not helpful. Sen. Ted Cruz (R-Texas), Trump's main GOP rival, doesn't know what he's talking about.
"People are making a lot of grandiose promises and pledges to do one thing or another, either on domestic affairs or on foreign policy," said Gates, who is promoting his new book, "A Passion for Leadership."
"But I haven't heard anybody really talking about how they would fix some of the problems that they're describing and how they would actually implement them," he added.
Gates went on to take an apparent swipe at Trump, who has proposed to build a wall along the US-Mexico border and "make Mexico pay for it."
"Some of the rhetoric in terms of how they would deal with problems is frankly totally unrealistic, in terms of making other countries do one thing or another, and so on," Gates told Business Insider.
"So what we're hearing," he added, "is people competing with each other to make ever-broader and more fantastic promises about all the things they're going to change that, in my experience, are completely incompatible with reality."
Gates has been struck by the phenomenon of both Trump and Sen. Bernie Sanders (I-Vermont), who has risen as an insurgent challenger to Clinton on the Democratic side.
But he took issue with what he called Trump's "over-the-top" rhetoric, particularly on foreign policy. Trump frequently professes at campaign rallies that his administration would "bomb the s--- out of" the Islamic State terrorist group, also known as ISIS. And Trump has been subject to intense criticism for a plan to temporarily bar Muslim tourists and immigrants from entering the country.
"How he intends to deal with issues is pretty unrealistic," Gates said of Trump.
Gates had perhaps even harsher criticism later in the week for Cruz, who has emerged as Trump's main threat on the Republican side. Cruz last year called for "carpet bombing" the Islamic State, an indiscriminate strategy that critics say would lead to large numbers of civilian casualties.
In a Tuesday "Morning Joe" interview, Gates said the tactic would be "totally useless" and end up backfiring on decades of US war strategy.