"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.
Graham said in the interview that he and the President discussed North Korea during a round of golf on Sunday and the issue "comes up all the time."
Those conversations are what led to Graham's candid prediction, an estimate that is based primarily on his own gut feeling about where the President stands on the issue, his spokesperson told CNN.
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 that he hopes military options are never employed and even advocated meeting with the North Koreans in pursuit of a peaceful resolution to tensions between the two nations.
"War with North Korea is an all-out war against the regime," he said, noting the extreme cost of a potential conflict on the Korean Peninsula. "There is no surgical strike option. So if you ever use the military option, it's not to just neutralize their nuclear facilities — you gotta be willing to take the regime completely down."
Graham also said he is "100% convinced that China is a rational actor" and indicated that a credible US threat of military force against North Korea could serve as a key strategic tool to pressure Beijing into stepping up its own efforts to rein in Pyongyang.
"They see North Korea as a thorn in our side — a problem for them, but the upside of North Korea is greater than the downside for them," Graham told The Atlantic.
"That changes, the day that they believe Donald Trump will blow up the whole place," he said, suggesting that a growing sense of urgency to resolve the situation before a potential conflict could prompt all parties to make the necessary concessions.
Graham has become increasingly vocal about the looming threat of a war with North Korea, and he said last month that the regime's advancing military technology makes the possibility of pre-emptive war more likely.
"I think we're really running out of time," he said, a view that is also shared by National Security Adviser H.R. McMaster.
McMaster, one of Trump's most trusted foreign policy aides, said Tuesday that the global community must "make the most out of what might be our last best chance" to avoid military action and he has repeatedly suggested that conflict is a real possibility.
But while Graham and McMaster seem to believe time is running out for the US to prevent Pyongyang from developing the capability of threatening the US with a nuclear weapon, some say the clock has already hit zero.
"A North Korean missile with a nuclear payload capable of striking an American city is no longer a distant hypothetical, but an imminent danger -- one that poses a real and rising risk of conflict," Sen. John McCain of Arizona, chairman of the Armed Services Committee, said during a recent hearing.
While the situation with North Korea demands urgency, one former senior defense official told CNN
last week that rhetoric being used by Graham and others is "damn scary" and potentially dangerous.
"I'm surprised people are talking so openly about starting a war with a nuclear power," the former official said, noting that leader Kim Jong Un is "reckless but not irrational" and is pursuing long-range nuclear weapons for deterrence -- a conclusion that is also shared by the CIA.
The Trump administration publicly insists that its "all-options-on-the-table" strategy has not changed and a senior administration official told CNN on Thursday that White House staffers were caught off guard by Secretary of State Rex Tillerson's offer this week to start talks
Tillerson's offer Tuesday to "sit down and see each other face to face" seemed to signal a shift in State Department policy, but US officials have since emphasized that North Korea has not yet demonstrated it is serious about talks or changing its behavior.
"We are open to the possibility of dialogue with North Korea, with the aim of denuclearizing the Korean peninsula. But North Korea must first refrain from any further provocations and take sincere and meaningful actions toward denuclearization," a National Security Council spokesperson told CNN.
Taking the advice of McMaster, Trump believes the time for talks with North Korea remains far off, according to the administration official, who added that Trump has said that he will make the final decision, and believes that foreign leaders and members of his administration know that.
The former senior defense official echoed that point last week, telling CNN that Trump could ultimately decide on his own whether or not the US makes the first move.
"The only reason we will have war is if President Trump wants war," the defense official said. "He is the wild card in this ... he can order us to start a war via a pre-emptive strike."