UNITED NATIONS — Three days after offering to talk to North Korea “without precondition,” Secretary of State Rex W. Tillerson reversed course, insisting — as President Trump has all along — that the North must stop its nuclear threats and “earn its way” to negotiations.

“A sustained cessation of North Korea’s threatening behavior must occur before talks can begin,” Mr. Tillerson said at a United Nations Security Council meeting.

His remarks on Friday were a sharp contrast from his surprisingly conciliatory comments, made Tuesday, in which he said he was open to talking to the North about anything, including, as he put it, “the weather.” The White House swiftly distanced itself, saying that talks would be pointless so long as the North continued to threaten its neighbors and the United States.

On Friday, Mr. Tillerson reiterated Mr. Trump’s position. “North Korea must earn its way back to the table,” Mr. Tillerson said. “The pressure campaign must and will continue until denuclearization is achieved.”