Representatives from the U.S. say North Korea's failure to shut down their main nuclear reactor has stalled the process but not derailed it.
The unobserved deadline marks the latest setback in an agreement reached earlier this year that provided hope that the communist country would move towards disarmament.
While in Beijing on Saturday, America's main negotiator fell short of openly criticizing the communist country.
"We don't have a lot of momentum right now. That is for sure," Assistant Secretary of State Christopher Hill said.
The disarmament plan was reached in February; just a few months after the North detonated a nuclear bomb in October.
It came after nearly four years of talks, and set out Saturday as a key milestone in the process.
The plan had been disrupted by a dispute over frozen North Korean funds in a Macau bank, but Washington said this past week that the disagreement was finally resolved.
On Friday, Hill would not say what the consequences would be if the deadline wasn't observed.
"There is no reason why the DPRK can't get on with the task of denuclearization," Hill said, using the official name of the Democratic People's Republic of Korea.
"We are not indifferent to missing a deadline. Obviously it is a very important date," he said. "We will work with our other partners on the appropriate response to the current circumstances."
Under the terms of the disarmament agreement, Pyongyang was to get access to $25 million in funds frozen in the Delta Asia bank in Macau.
The U.S. had blacklisted the bank for allegedly laundering money for the North and helping it pass counterfeit $100 bills.
The money was supposed to be available to the North this week, but on Friday the country's foreign ministry said it couldn't confirm that had taken place.
However, at that time Pyongyang said it would hold up its end of the bargain and shut down the reactor once the money was released.
In February, after boycotting talks for 13 months, the North agreed with the U.S., China, South Korea, Japan and Russia to give up its nuclear programs in exchange for energy aid and political concessions, along with the U.S. promise to solve the Macau issue.
With files from The Associated Press
