“No matter what options the United States and President Trump want to use, they have promised to have full consultation with South Korea and get our consent in advance,” Mr. Moon said in a nationally televised news conference. “This is a firm agreement between South Korea and the United States. The people can be assured that there will be no war.”

He said he thought Mr. Trump’s combative recent statements had been meant to “demonstrate his resolve and put pressure on North Korea.”

“I don’t think he necessarily made them with an intent to realize a military action,” said Mr. Moon, whose office said that it remained in contact with the White House, including a phone call between the leaders last week. “On this, there is sufficient communication and agreement being made between South Korea and the United States.”

In his interview with the magazine The American Prospect Mr. Bannon said the fact that Seoul, South Korea’s capital, lies in range of the North’s conventional weapons ruled out a military solution.

“Until somebody solves the part of the equation that shows me that 10 million people in Seoul don’t die in the first 30 minutes from conventional weapons, I don’t know what you’re talking about, there’s no military solution here, they got us,” Mr. Bannon was quoted as saying.

Mr. Bannon said the North Korea issue was a “sideshow” to what he called America’s “economic war with China,” the North’s sole major ally. He said the United States should stop hoping that Beijing would use its influence to rein in Pyongyang, and should instead proceed with tough trade sanctions against China.

Image The chief White House strategist Steve Bannon. Credit... Alex Brandon/Associated Press

Mr. Bannon’s statements are not likely to shift American policy. He no longer has a seat on the National Security Council, and has not been actively involved in North Korea policy, according to several officials. Mr. Bannon cares about North Korea, these officials said, to the extent that he views it as distracting from his effort to prosecute a trade campaign against China.