WATCH: Ex-Pentagon official issues dire warning: Judiciary and Congress are the only things that can protect us from Trump
NNBC News national security analyst Jeremy Bash (screengrab)

The former chief of staff at the CIA and Pentagon warned America about the dwindling number of checks on President Donald Trump.

Jeremy Bash, a national security analyst for NBC News, joined the "11th Hour" with anchor Brian Williams on Tuesday.

Williams asked Bash about acting Attorney General Matt Whitacker.

"Well, he has to be a check against the president, but he was put in there to not be a check," Bash noted. "So really the only checks left in our government are those in Congress."

"And just to think big, for a moment, the president is redefining the American presidency before our eyes -- or he's attempting to," Bash warned.

"He's attempting to redefine American democracy," he continued. "In our system of checks and balances, the only branches of government that can stop a president from doing these illegal acts are the judiciary and the Congress."

Williams asked Bash to reply to a tweet sent by former acting Attorney General Sally Yates.

"This is a bipartisan view that we hear time and time again -- from professionals, career law enforcement, intelligence and military professionals -- that the president is abusing his authority as commander-in-chief," he noted.

"We've never seen anything like it in our history," Bash added.