Cabinet meeting in London
British Defence Secretary Ben Wallace walks on Downing Street in London, Britain, March 7, 2023. Reuters

Britain on Tuesday played down the impact from the leaks of highly classified U.S. intelligence documents online, saying some of the information being circulated from them was untrue and manipulated, without offering specific examples.

A 21-year-old member of the U.S. Air National Guard accused of leaking top secret military intelligence records online was arrested last week and charged with unlawfully copying and transmitting classified material.

The leaks are believed to be the most serious U.S. security breach since more than 700,000 documents, videos and diplomatic cables appeared on the WikiLeaks website in 2010.

Still, Ben Wallace, the British defense minister, told reporters in Washington that he observed inaccuracies in his review of the published information. He urged the public to be skeptical of the leaked material.

"I'm not going to comment on a specific part of the leak, but I have seen in our media a number of inaccuracies, significant inaccuracies, or manipulation of information," Wallace said.

"My advice is don't take it at face value."

He said the leak had "absolutely not" damaged relations with the United States and would not strengthen Russia or weaken Ukraine in their conflict.

Reuters reviewed some of the leaked documents, which included one that asserted that Britain, the United States and other countries had military special operations forces operating inside Ukraine. The Pentagon has said U.S. forces in Ukraine operate from the embassy and help track U.S. weapons provisions to Kyiv to help it defend itself against invading Russian forces.

The Washington Post reported on a leaked Defense Intelligence Agency assessment it says it obtained that anticipated 2023 will end without any Ukraine battlefield breakthrough for either side.

Without commenting on the documents themselves, Wallace expressed confidence in Ukraine's battlefield momentum, played down the idea of a stalemate and dismissed any characterization of the war as a "frozen conflict."

"The momentum is still with them. It may not be whoosh bang momentum but it is certainly forward -- and momentum matters," Wallace said.