What happened? 
On 21 September, during a televised address to the nation, Russia's President Vladimir Putin commented on three pressing issues of the ongoing war. Referring to the ongoing fighting in the Donetsk region, he stressed supplying military and other equipment to the volunteer units and the militia of the Donbas region. Next, Putin points out that the parliaments of the Donbas people's republics and the military-civilian administrations of Kherson and Zaporizhzhia have decided to hold their referendums in the coming days. Following it, Putin announced a 'partial mobilization,' beginning the same day, and added that the defence industry enterprises would be responsible for increasing production and meeting the new demands. 
Putin explained, "Washington, London and Brussels are openly encouraging Kyiv to move the hostilities to our territory. They openly say that Russia must be defeated on the battlefield by any means, and subsequently deprived of political, economic, cultural and any other sovereignty and ransacked." Further, he claims that the West has resorted to nuclear blackmail, and promised to use all weapon systems available to Moscow to defend the country and its people. 

What is the background? 
First, a context to Putin's speech and the Ukrainian counteroffensive. It comes during the Ukrainian counteroffensive of late August. It led to the consolidation of the Russian troops in specific pockets of Ukraine. The Ukrainian counteroffensive is ongoing in the Russian-occupied regions in Kharkiv from the northeast, Donetsk in the north, and Kherson from the south. The active financial support of the West, the military equipment aide from NATO, and the support of highly efficient satellites, drones, artificial intelligence, and cyber capabilities supported by western commercial technology companies have aided the Ukrainian counteroffensive efforts and helped recapture an estimated 8000 square kilometres of territory, primarily in the northeast. These losses and the strong Western support for Ukraine have pushed Russia to consider dire measures. 
Second, the referendum in Kherson, Zaporizhzhia, and Donbas regions. Though Russia formally recognizes the Ukrainian post-Soviet borders under the 1994 Budapest Memorandum, Putin is said to consider swathes of eastern and southern Ukraine to be Russian possessions lost due to mistakes by Soviet leaders Lenin and Khrushchev. On 20 September, the authorities of the occupied regions announced that referendums would be held between 23 September to 27 in Donbas and the military administrations of Kherson and Zaporizhzhia. Russia controls most of Luhansk and Kherson, around 66 per cent of Zaporizhzhia and 60 per cent of Donetsk. The referendums that began on 23 September are considered illegal under Ukrainian and international law. 
Third, partial mobilization. Putin's announcement aims to bring together 300,000 reservists. This is three times the size of the initial forces deployed by Russia in February and 15 per cent of Russia's estimated total conscription potential. In early July, Russia launched a volunteer recruitment drive unsuccessfully. Heavy losses during seven months of the war, the estimated loss is 6000- 20,000 troops lost based on Russian and US estimates and clear indications of a drop in morale. Ukrainian military intelligence revealed that Russia has deployed special units to fill in for deserters. On 20 September, Russia announced jail terms of 10-15 years for soldiers that surrender, desert or fail to report for military duty.
Fourth, Putin's response to the western nuclear threat. In his speech, Putin stated, "If the territorial integrity of our country is threatened, we will use all available means to protect Russia and our people - this is not a bluff." He claimed that the West was engaging in a ‘nuclear blackmail,’ accusing them of crossing every line. 

What does it mean?
The call for partial mobilization shows that Russia is willing to escalate their war efforts in the region despite the counteroffensive, with an expectation of a long-drawn war. The ongoing referendum paves the way for Moscow to bring the regions under the Russian Federation. If voted in favour of Russia, a dramatic escalation in the war after seven months is expected. The parties to the war continue to claim the referendum as being staged and call it a sham. 
Russia is witnessing sporadic protests against mobilization. Over 1000 protesters were detained, mainly in Moscow and St Petersburg. Many Russians were also seen attempting to flee the country through the borders of Finland, Mongolia, and Serbia; some are known to have fled to countries like Turkey, Armenia and Azerbaijan. There remains a sense of rejection of the continuation of the war efforts of Russia and a fear of losing lives on the battlefield.