According to documents obtained by the Ukrainian military and shared with The Guardian, Russia's military command foresaw Ukraine's August 6 incursion and failed to act on warnings from those in the region. Newsweek has contacted the Russian Ministry of Defense for comment on the reports.

Russian commanders anticipated that Ukraine was planning an incursion into Kursk Oblast months before it occurred, the Guardian reported on Sept. 20, citing a collection of documents that Ukrainian soldiers said they had seized from abandoned Russian positions.

Russia said on Friday that its army would regain control of its Kursk region "in a timely manner", declining to say how soon this could be achieved. Ukraine on Aug. 6 launched the biggest foreign attack on Russia since World War Two,