Two former national security officials said Sunday they don't agree with the saber-rattling rhetoric of President Donald Trump's pick to become the new national security chief.

John Bolton, a former U.S. ambassador to the United Nations and proponent of the 2003 Iraq War best known for his hawkish views, has spoken in interviews about the need for pre-emptive strikes against North Korea. Trump's appointment of Bolton last week raises questions about whether he will take a militaristic approach, said retired Adm. Mike Mullen, who served as chairman of the Joint Chiefs of Staff under Democrat and Republican presidents.

"I wonder, are we going backwards in terms of those countries we've focused on the past, and the 'axis of evil,' the ones that still present huge challenges for us," Mullen said on ABC's "This Week."