In an interview on ABC's "This Week," Mullen warned that President Donald Trump's provocative rhetoric aimed at North Korean leader Kim Jong Un likely indicates he would prefer to take a more aggressive approach to countering the rogue regime's rapidly evolving nuclear weapons program.
"I'm just more inclined to see over time that the rhetoric seems to be where the President is," Mullen said, adding that Defense Secretary James Mattis, national security adviser H.R. McMaster and White House chief of staff John Kelly have managed to deter Trump from following through on his threats of unleashing "fire and fury."
"My concern is how long that actually lasts," Mullen said, adding that, at some point, Trump may be inclined to ignore advice from his top national security advisers that runs counter to his own instincts.
The North Korean leader addressed the threat of war in a New Year's Day speech on Monday.
"We are a responsible nuclear nation that loves peace," Kim said. "As long as there's no aggression against us we do not intend to use nuclear powers."
"The US cannot wage a war against our country at all," Kim added. "The entire mainland of the US is within the range of our nuclear weapons, and the nuclear button is always on the desk of my office. They should accurately be aware that this is not a threat but a reality."
A year of 'extreme danger'
Mullen's warning about the possibility of war with North Korea was echoed by Republican Sen. Lindsey Graham, of South Carolina, who said Sunday that 2018 could be a year of "extreme danger."
"We've got a chance here to deliver some fatal blows to some really bad actors in 2018. But if we blink, God help us all," Graham said in an interview
on CBS's "Face the Nation."
Earlier this month, Graham predicted that there is a 30% chance Trump orders a first strike on North Korea to prevent the rogue nation from acquiring a nuclear weapon capable of hitting the United States.
"I would say there's a three in 10 chance we use the military option," the South Carolina Republican first said in an interview with The Atlantic
and later confirmed to CNN
. If the North Koreans conduct an additional test of a nuclear bomb — their seventh — "I would say 70 percent," he said.
While Graham, an Air Force veteran who serves on the Senate Armed Services Committee, is widely considered a Republican foreign policy hawk, he repeatedly said in the interview with The Atlantic that he hopes military options are never employed and advocated meeting with the North Koreans in pursuit of a peaceful resolution to tensions between the two nations.
In his interview Sunday, Graham said his prediction on the chance of a war with North Korea is "based on a lot of time with President Trump."
"He made a decision early on to deny the North Korean regime the capability to hit America with a nuclear-tipped missile," including the use of military force, if necessary, Graham said.
Asked if he thought that meant a pre-emptive strike in the coming year, Graham said: "2018 is going to be the year to deny North Korea the capability to hit the homeland. Sanctions will never work completely without the threat of credible military force. How do you change a man's behavior who's willing to kill his own family, torture his own people to stay in power?"
"The only way he'll change his behavior, if he believes Donald Trump would use military force to destroy his regime," Graham added. "And the Iranians are watching how Trump deals with North Korea."
A report released Saturday by North Korea's state-run Korean Central News Agency said the country will remain committed to nuclear development in 2018.
"Do not expect any change in its policy," the report read.
"Its entity as an invincible power can neither be undermined nor be stamped out. The DPRK, as a responsible nuclear weapons state, will lead the trend of history to the only road of independence and justice, weathering all tempests on this planet," the report continued, referring to North Korea's official name, the Democratic People's Republic of Korea.