Key Events of the Second Period of the Armed Conflict in the East of Ukraine (05. 09. 2014 – 30. 04. 2018)

The article aims to structure the accumulated factual material about the Russian Federation's armed aggression against Ukraine, which began on 20 February 2014 and developed a historical periodization variant. The research's main result is that the authors prove that the Russian Federation's armed aggression caused the armed conflict in the East of Ukraine. The authors set out the actual course of the main events in chronological sequence and determined the Russian-Ukrainian armed confrontation's key milestones at the beginning of the 21st century. According to the nature of military operations, military-political results and the consequences of the armed conflict in the East of Ukraine, it is divided into periods within which stages are distinguished, qualitatively different in purpose, nature and content of combat (special) operations. To repulse and deter this aggression, Ukraine used the forces of the security and defence sector. The form of these forces employment from 14 April 2014 to 30 April 2018 was the Anti-Terrorist Operation, and after – the Joint Forces Operation. This military-historical study creates the basis for further scientific research on the study of the armed conflict in the East of Ukraine. Such research is necessary to have a clearer understanding of the nature and essence of Russia's hybrid war against Ukraine, a more in-depth analysis of its evolution, and broader dissemination of lessons learned in the course of countering hybrid threats in the military sphere.