The Royal United Services Institute for Defence and safety Studies (known to a wider audience most frequently as RUSI) leaned over the issue of preliminary experiences from the war in Ukraine. The authors, i.e. Mykhayl Zabrodskyi, Jack Watling, Oleksandr V Danylyuk and Nick Reynolds (recording names and names according to the English version of the report), selected for analysis the period from February to July 2022, divided their work into 5 visible chapters, covering issues of Russian preparations for aggression, Ukrainian defence preparations, analysed the course of the invasion from 0 to +91. In their work, they besides considered issues related to the assessment of Russian armed actions and repercussions, as well as a very interesting summary of selected suggestions for the British armed forces.