On 30 September 2022, Russia, amid an ongoing invasion of Ukraine, unilaterally declared its annexation of areas in and around four Ukrainian oblasts—Donetsk, Kherson, Luhansk, and Zaporizhzhia. Most of Luhansk Oblast and part of Donetsk Oblast had been controlled by pro-Russian separatists since 2014, while the Kherson and Zaporizhzhia Oblasts were invaded by Russia in 2022. The boundaries of the areas to be annexed and their borders were not defined; Russian officials stated that they would be defined later. None of the oblasts were fully under Russian control at the time of the declaration, nor since. If limited to the areas then under Russian control (about 90,000 km or 15% of Ukraine's territory, roughly the size of Portugal) the annexation would still be the largest in Europe since World War II.
The move occurred after internationally unrecognized referendums held days prior, which were organized by Russian occupation authorities in territories where hostilities were ongoing and much of the population had fled. It occurred seven months after the start of the invasion and less than a month after the start of the Ukrainian Kharkiv counteroffensive. The signing ceremony was held in the Grand Kremlin Palace in Moscow in the presence of occupation authority heads Leonid Pasechnik, Denis Pushilin, Yevgeny Balitsky and Vladimir Saldo, and Russian president Vladimir Putin.
