Why Russia-Ukraine War is caused ?

[6/6, 11:31 AM].: Russia–Ukraine relations are the bilateral ties between the Russian Federation and Ukraine. Following the Ukrainian Revolution of Dignity in 2014, Ukraine's Crimean Peninsula was occupied by unmarked Russian forces, and later annexed by Russia, while pro-Russia separatists simultaneously engaged the Ukrainian military in an armed conflict for control over eastern Ukraine; these events marked the beginning of the Russo-Ukrainian War. In a major escalation of the conflict on 24 February 2022, Russia launched a full-scale invasion of the Ukrainian mainland across a broad front, causing Ukraine to sever all formal diplomatic ties with Russia

[6/6, 11:31 AM] : After the collapse of the Soviet Union in 1991, the successor states' bilateral relations have undergone periods of ties, tensions, and outright hostility. In the early 1990s, Ukraine's policy was dominated by aspirations to ensure its sovereignty and independence, followed by a foreign policy that balanced cooperation with the European Union (EU), Russia, and other powerful polities.[4]

Relations between the two countries became hostile after the 2014 Ukrainian revolution, which was followed by Russia's annexation of Crimea from Ukraine, and due to Russia's backing for the separatist fighters of the Donetsk People's Republic and the Luhansk People's Republic in a war, conflicts that had killed more than 13,000 people by early 2020, and brought Western sanctions on Russia.[5] Numerous bilateral agreements have been terminated and economic ties severed.

Throughout 2021 and 2022, a Russian military buildup on the border of Ukraine escalated tensions between the two countries and strained their bilateral relations.[6][7] Ukraine broke diplomatic relations with Moscow in response to Russia's invasion of Ukraine. Streets bearing the names of Russian figures and monuments symboling Russia and Ukraine friendship were removed from various locations across Ukraine.

[6/6, 12:04 PM] : At the start of the invasion, Russian attacks were launched on a northern front from Belarus towards Kyiv, a northeastern front towards Kharkiv, a southern front from Crimea, and a southeastern front from the cities of Luhansk and Donetsk.[43][44] During March, the Russian advance towards Kyiv stalled. Amidst heavy losses and strong Ukrainian resistance, Russian troops retreated from Kyiv Oblast by 3 April. On 8 April, Russia announced that its forces in southern and eastern Ukraine would be placed under the command of General Aleksandr  and some units withdrawn from northern Ukraine were subsequently redeployed to the Donbas.[45] On 19 April, Russia launched a renewed attack across 500000 meters (300 mi) long front extending from Kharkiv to Donetsk and Luhansk, with simultaneous missile attacks directed at Kyiv in the north and Lviv in western Ukraine.[46] By 13 May, Russian forces near Kharkiv had withdrawn following a Ukrainian counter-offensive. By 20 May, Mariupol fell to Russian troops following a prolonged siege of the  steel works.

Russian soldiers without insignia took control of strategic positions and infrastructure in the Ukrainian territory of Crimea, and seized the Crimean Parliament. Russia organized a controversial referendum, whose outcome was for Crimea to join Russia. This led to the annexation