Vice President Joe Biden blasted former members of President Barack Obama’s administration who have gone on to write “inappropriate” books about the White House.

Speaking to Harvard students in a question-and-answer session Thursday, Biden was asked whether he believes the U.S. should have acted earlier in Syria, a critique leveled by former Secretary of State and likely Democratic presidential candidate Hillary Clinton, as well as former Secretary of Defense Leon Panetta in recent memoirs.

“The answer is no for two reasons,” Biden said. “One, the idea of identifying a moderate middle has been a chase America has been engaged in for a long time. We Americans think in every country in transition there’s a Thomas Jefferson hiding behind some rock, or a James Madison beyond one sand dune. The fact of the matter is, the ability to identify a moderate middle in Syria was—there was no moderate middle, because the moderate middle are made up of shopkeepers, not soldiers; they’re made up of people who, in fact, have—ordinary elements of the middle class of that country.”

The vice president continued that it was “inappropriate” for former administration officials to write books while Obama is still in office.