Former National Security Agency director and CIA director Michael Hayden expressed concern about President-elect Donald Trump’s pick for national security advisor, Michael Flynn, saying Flynn, the former director of the Defense Intelligence Agency, would be “stretched a bit” by his new role.

“But by and large he’s been successful at the tactical operational level,” Hayden said during an appearance on ABC’s “This Week.” “This is a strategic global job. And so I think he’ll be stretched a bit by this.”

Trump’s choice of Flynn was met with alarm in many circles for his repeated anti-Muslim comments. “Fear of Muslims is RATIONAL: please forward this to others: the truth fears no questions,” Flynn tweeted in February. He has repeatedly called Islam a “political ideology,” a “cancer” and said the Islamic world is a “failure.”

Flynn was fired from his DIA job in 2014, which he claimed was over disagreements with President Barack Obama on his approach to combatting terrorism. Since that time, Flynn’s consulting firm, The Flynn Intel Group, has come under scrutiny for its ties to the government of Turkish strongman Recep Tayyip Erdoğan and a number of Middle Eastern governments. Flynn has also since accepted a paid speaking engagement with the Russian government-backed Russia Today television network.

Though Hayden confined his remarks about Flynn to his role as a military intelligence official, he appeared to indirectly criticize Flynn’s increasing tendency for alarmist statements and behavior, by citing the equanimity and intellectual rigor of past national security advisors.

“Mike’s got great ideas. But unless you’re hiring a Kissinger or a Brzezinski or a Scowcroft in that job, what you really want is a process guy in the job, the one who tees up issues, makes sure all elements of the government have a voice,” Hayden said, referencing former national security advisors Henry Kissinger, Zbigniew Brzezinski and Brent Scowcroft. “So that’s going to extend Mike as well.”