Despite not controlling any of the four provinces and its troops retreating in the face of major military losses, Russian President Vladimir Putin signed legislation on Wednesday that finalized the annexation of four Ukrainian regions.
Around 15% of Ukrainian territory was formally incorporated into Russia by Putin.
The Russian president's approval is the final step in the annexation process and is illegal under international law.
The Russian-imposed leaders of the annexed regions were appointed by Putin.
It is not clear where the Kremlin believes Russia's new international borders lie, something officials admit is a work in progress.
The major advances into occupied territory by Ukrainian troops, who reportedly brought Russian forces in southern Ukraine to the brink of collapse late Tuesday and forced a hasty retreat, have not stopped Putin from continuing his annexation efforts.
Russia has lost a lot of territory in recent weeks and the move raises more questions about how Moscow will defend it.
The Russian parliament unanimously approved the annexation plans on Monday and Tuesday. After a series of referendums held last week, the four regions decided to join Russia, according to the Kremlin. The annexation effort has been condemned by the leader of the UN.
Angry protests and a rush of people fleeing to neighboring countries were caused by Putin's announcement of the partial deployment of Russian forces. Putin said that Moscow would defend its territory with all of its weapons. The use of tactical nuclear weapons is more likely due to the mounting pressures on the Russian leader.
The retreat of Russian forces in the southern Kherson region has been classified by the Ukrainian government as an orderly and tactical retreat by the Russians. The nature of the region will be important for future developments, but it is not clear which interpretation is more accurate.
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Russia is sending its ethnic minorities to the meat grinder.