Analysts at the Institute for the Study of War (ISW) have noted that the Ukrainian military was able to take advantage of the situation to launch its operation in Russia's Kursk Oblast, despite the fact that Russia had known about and had been preparing for it for months.

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.

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,