The U.S. military has said that "a human error in labeling" led to the accidental classification of previously available information about the war in Afghanistan.
Captain Tom Gresback, a spokesman for the NATO-led Resolute Support mission in Afghanistan, said in a January 30 statement that "it was not the intent of Resolute Support to withhold or classify information which was available in prior reports."
The statement came one day after an independent federal auditor, the Special Inspector-General for Afghanistan Reconstruction (SIGAR), stated in its quarterly report that it was told not to release data on the amount of territory controlled or influenced by the Taliban and the government.
The military also classified information about the size of the Afghan military and police forces.
"This development is troubling for a number of reasons, not least of which is that this is the first time SIGAR has been specifically instructed not to release information marked 'unclassified' to the American taxpayer," SIGAR John F. Sopko wrote in the report.
"Aside from that, the number of districts controlled or influenced by the Afghan government had been one of the last remaining publicly available indicators for members of Congress -- many of whose staff do not have access to the classified annexes to SIGAR reports -- and for the American public of how the 16-year-long U.S. effort to secure Afghanistan is faring," he added.
The Western-backed government in Kabul has been struggling to fend off the Taliban and other militant groups since the withdrawal of most NATO troops in 2014.
Kabul in recent weeks has been hit by several deadly assaults, including a massive suicide car bombing in a crowded central area on January 27 that killed more than 100 people and was claimed by the Taliban.
On January 29, U.S. President Donald Trump rejected the possibility of negotiations with the Taliban anytime soon.
"We don't want to talk with the Taliban," Trump said. "There may be a time, but it's going to be a long time."
"We're going to finish what we have to finish" in Afghanistan, he also said.
Trump in August unveiled his new strategy for the South Asia region, under which Washington has deployed 3,000 more troops to Afghanistan to train, advise, and assist local security forces, and to carry out counterterrorism missions.
The United States currently has around 14,000 uniformed personnel in the country.