Annexation of Crimea by the Russian Federation military intervention in Ukraine "until normalization of a socio-political environment in the country". Putin's swift manoeuvre prompted protests of intelligentsia and demonstrations in Moscow against a Russian military campaign in Crimea. By 2 March, Russian troops moving from the country's naval base in Sevastopol and reinforced by troops, armour, and helicopters from mainland Russia exercised complete control over the Crimean Peninsula. Russian troops operated in Crimea without insignia. On 4 March Ukrainian General Staff claimed there are units of 18th Motor Rifle Brigade, 31st Air Assault Brigade and 22nd Spetsnaz Brigade deployed and operating in Crimea instead of Russian Black
Annexation of Crimea by the Russian Federation also signed the Budapest Memorandum on Security Assurances, by which all these countries reaffirmed their obligation to respect the territorial integrity of Ukraine (including Crimea) and to refrain from the threat or use of force against the territorial integrity or political independence of Ukraine. According to the Constitution of Russia, the admission of new federal subjects is governed by federal constitutional law (art. 65.2). Such a law was adopted in 2001, and it postulates that admission of a foreign state or its part into Russia shall be based on a mutual accord between the Russian Federation and the relevant state