Secretary of State Rex Tillerson said North Korea must "earn its way back to the table" before talks can begin.
"The pressure campaign must, and will, continue until denuclearization is achieved. We will, in the meantime, keep our channels of communication open," Tillerson said.
Tillerson's statement during Friday's United Nations Security Council meeting strikes a different tone than one he made earlier in the week. During the Atlantic Council meeting, he said it's not realistic to expect the North to come to the table ready to denuclearize.
"When do the talks begin? We've said from the diplomatic side we're ready to talk anytime North Korea would like to talk, and we're ready to have the first meeting without precondition," Tillerson said on Dec. 13.
That remark caused the White House to reiterate President Trump's views on the situation "have not changed."
Since the spring, the U.S. has run what it calls a "peaceful pressure campaign" against North Korea. Leaders hope widespread economic and diplomatic sanctions will pressure the North to end its nuclear program.
The sanctions are estimated to decrease North Korea's export revenue by $2.3 billion. Tillerson said the country is already experiencing shortages and an increase in fuel prices.
During the U.N. meeting, Tillerson urged countries to continue to stick to the sanctions and specifically called out Russia and China to increase pressure.
As long-term allies of North Korea, the two countries are key players in enforcing the sanctions. Tillerson referenced China's decision to cut off North Korea from oil in the past was a successful tactic.
Trump has also said that "Russia's not helping" and spoke with Russian President Vladimir Putin over the phone Thursday about working together on the situation.