The war on Ukraine, which the Russian Federation launched in February 2022, has continued nearly 4 years at the end of 2025 and there are no significant progress of ceasefire talks between both sides, started by mediation of U.S. Donald Trump Administration from the beginning of that year. Many political leaders, journalists and commentators in Europe, United States and Japan have insisted that Russian President Vladimir Putin was planning to obtain the whole territory of Ukraine and even would invade North Atlantic Treaty Organization（NATO）member states in Europe if they could not stop Russian military actions inside of Ukraine.
Chikamasa SATO (2025) studied this question.