President Trump speaks at a meeting with Defense Secretary Jim Mattis on Thursday in the Cabinet Room of the White House. (Jabin Botsford/The Washington Post)

MUSCAT, Oman — Defense Secretary Jim Mattis said he does not want to talk about the Korean Peninsula “at all” at this time, underscoring the sensitivity with which he believes Washington must handle a potential meeting between President Trump and North Korea leader Kim Jong Un.

Mattis, speaking on a military flight from Washington to the Middle East, said media questions about North Korea are “very valid,” but he will leave it to the State Department and senior members of the White House to address questions about the meeting because it is a diplomatically led effort. The Pentagon chief addressed the issue for the first time since Trump unexpectedly accepted an invitation Thursday to meet with Kim after years of his regime’s threats against the United States and South Korea.

“When you get into a position like this, the potential for misunderstanding remains very high or grows higher,” Mattis said. “So, I want those who are actually engaging in the discussions to be actually the ones who answer all media questions.

Trump met Thursday with South Korean national security adviser Chung Eui-yong, who relayed an invitation to Trump to meet with Kim. Chung said it came with a promise that Kim would temporarily stop his ballistic missile and nuclear weapons programs and an acknowledgment that the South Korean and U.S. militaries would continue to carry out exercises together.

The meeting potentially provides a framework through which the two Koreas and the United States can de-escalate years of tension that ratcheted up as the Kim regime tested nuclear bombs, launched ballistic missiles over Japan and threatened to destroy U.S. cities. But if the meeting fails, it could leave Trump and his senior advisers feeling as though there is no alternative with North Korea but war.

Trump signaled Saturday night in Pennsylvania that he’s uncertain what is to come.

“Who know what’s going to happen?” he said, speaking at campaign rally for Republican congressional candidate Rick Saccone. “I may leave fast, or we may sit down and make the greatest deal in the world.”

Mattis, asked about the military aspects of the discussions, declined to answer.

“If I was sitting on your side of this cabin I’d be doing the same thing,” Mattis told a reporter on his plane asking the question. “What I want you to understand is that right now every word is going to be nuanced and parsed apart across different cultures, at different times of the day, in different contexts.”

The approach is in keeping with Mattis’s desire to put diplomacy at the forefront with military might underpinning it. The Pentagon chief, a retired Marine general known to have influence with Trump, has repeatedly stressed looking for ways to avoid war with North Korea.

The military dimensions to the talks are not all clear but include annual military exercises that are expected to begin within weeks. The largest, known as Foal Eagle, typically involves thousands of U.S. troops drilling with an even larger South Korean force. Last year’s exercise included everything from a visit by the aircraft carrier USS Carl Vinson to participation for the first time by advanced F-35B fighters. North Korea has typically responded to the exercises with outrage.

Trump also addressed the potential talks with two tweets Saturday afternoon, saying in the first that he had discussed the potential meeting with North Korea “at length” with Chinese President Xi Jinping.

“President Xi told me he appreciates that the U.S. is working to solve the problem diplomatically rather than going with the ominous alternative,” Trump wrote. “China continues to be helpful!”

Trump noted in a second tweet that North Korea has not conducted a missile test since Nov. 28 and has “promised not to do so through our meetings.” Trump believes North Korea will honor that commitment, he wrote.