Putin gave an "explicit warning that Russia perceived NATO's eastward expansion as a threat to its national security" as early as 2007 in his Munich speech [0]. The Russo-Ukrainian war began in 2014 with the ouster of Yanukovych, who was pro-Russia and opposed closer ties with the EU [1]. Zelensky became president in 2019 and initially promised to end the Russo-Ukranian war, but instead continued to pursue NATO protection and in August 2021 "urged NATO members to speed up Ukraine's request for membership" [2]. Russia escalated the Russo-Ukrainian war and invaded Ukraine for a second time in February 2022 [3].
Putin gave an "explicit warning that Russia perceived NATO's eastward expansion as a threat to its national security" as early as 2007 in his Munich speech [0]. The Russo-Ukrainian war began in 2014 with the ouster of Yanukovych, who was pro-Russia and opposed closer ties with the EU [1]. Zelensky became president in 2019 and initially promised to end the Russo-Ukranian war, but instead continued to pursue NATO protection and in August 2021 "urged NATO members to speed up Ukraine's request for membership" [2]. Russia escalated the Russo-Ukrainian war and invaded Ukraine for a second time in February 2022 [3].
[0] https://en.wikipedia.org/wiki/2007_Munich_speech_of_Vladimir...
[1] https://en.wikipedia.org/wiki/Russo-Ukrainian_War
[2] https://en.wikipedia.org/wiki/Volodymyr_Zelenskyy
[3] https://en.wikipedia.org/wiki/Russian_invasion_of_Ukraine