This timeline of the Russo-Ukrainian war covers the period from 1 December 2023 to 31 March 2024.

This period was characterized by an increased reliance on drones and missiles amid an increasing shortage of Ukrainian artillery ammunition and tanks.

December 2023 1 December Ukraine claimed that Russian forces launched 25 Shahed drones and one Kh-59 missile. Ukrainian forces claimed to have downed 18 of the drones and the missile.

Ukraine said it had successfully tested domestically made electromagnetic warfare systems to protect soldiers from radar-guided weapons and drones.

Ukrainian media reported that the Security Service of Ukraine (SBU) was behind another bomb attack on a fuel train passing over a rail bridge on the Baikal-Amur Mainline in the Russian Far East. Ukrainian military intelligence (HUR) claimed that a Russian military refueling station in Melitopol was blown up by partisans, killing several soldiers and damaging military equipment.

The Russian FSB claimed to have arrested a dual Italian-Russian citizen in relation to the derailing of a freight train near Rybnoye, Ryazan Oblast on 11 November. The FSB claimed that he had been recruited in February 2023 and received training in Latvia.

Two pro-Russian separatists from the Donbas captured by Ukraine were sentenced to 12 years in prison for treason.

Russian President Vladimir Putin signed a decree increasing the number of Russian military personnel by 170,000, with the Russian Defence Ministry citing NATO expansion and the war in Ukraine as one of the reasons for the decree.

In an interview with the Associated Press in Kharkiv, Ukrainian President Volodymyr Zelenskyy acknowledged that the Ukrainian counteroffensive "did not achieve the desired results", and said the war had entered a new phase with the winter season.

Germany delivered a military aid package to Ukraine that included four HX81 tractors, eight Zetros off-road trucks, four other vehicles, 15 HLR 338 precision rifles, 60,000 rounds of ammunition, five drone-detection systems, laser range finders, and more than 4,000 155 mm shells.

The US imposed sanctions on three transnational firms for violating a price cap imposed by the US Treasury Department on Russian oil in response to the invasion of Ukraine.

The International Federation of Red Cross and Red Crescent Societies suspended the membership of the Belarus Red Cross after it refused to remove its head Dzmitry Shautsou, who admitted involvement in the deportation of Ukrainian children from Russian-occupied territories.

2 December Ukraine released a video reportedly showing two unarmed Ukrainian soldiers being executed by Russian soldiers after surrendering near the frontline village of Stepove, Donetsk Oblast. The Ukrainian military later said that the perpetrators were killed on 4 December.

The SBU said that it had prevented former Ukrainian president Petro Poroshenko from going to Hungary to meet with Prime Minister Viktor Orban, saying that Russia was planning to use the meeting "in psychological operations against Ukraine."

3 December Three people were killed in separate Russian attacks in Donetsk and Kherson oblasts.

4 December The SBU said it had launched two drone strikes that destroyed Russian ammunition and equipment depots near Svatove, occupied Luhansk Oblast. It also arrested a resident of Kyiv on suspicion of aiding Russian airstrikes on the capital and a businessman for trying to sell stolen aircraft components to Russia.

Nepal confirmed that six of its nationals had been killed while fighting for Russia in Ukraine and that a seventh was captured. CNN later estimated that Russia had recruited thousands of Nepalis to fight its war.

The Biden administration warned that funding for Ukrainian military aid would run out by the end of the year and requested more funding from the US Congress. Bulgarian president Rumen Radev vetoed an agreement to donate to send 100 surplus APCs to Ukraine, sending the arrangement back to the National Assembly for reconsideration. The assembly subsequently voted to override Radev's veto on 8 December.

5 December

Two people were killed in a Russian attack on Kherson. One person was killed in a separate attack in Donetsk Oblast.

The UK Ministry of Defence assessed that Russian forces were in control over most of Marinka, with Ukrainian forces retaining control over "pockets of territory in the western edge of the town".

The Ukrainian Air Force claimed to have shot down a Russian Su-24M bomber aircraft preparing to launch airstrikes near Snake Island with an anti-aircraft missile from an Su-30SM fighter plane.

Russia claimed to have shot down 35 Ukrainian drones over Crimea. Ukrainian media reported that the Marine Oil Terminal in Feodosia, a Nebo-M radar system near Baherove, as well as a military helicopter parking lot, a P-18 Terek radar complex, and a Baikal-1M anti-aircraft missile control system were targeted in the attacks, causing significant damage.

The US imposed sanctions on the head of the Belarus Red Cross, Dzmitry Shautsou, for his role in the deportation of Ukrainian children from Russian-occupied territories, and on Belgium-based businessman Hans de Geetere, who is alleged to lead an international network procuring sophisticated electronics with potential military applications for Russia-based end-users.

6 December Ukrainian media reported that former MP Illia Kyva, who fled to Russia after the 2022 invasion and subsequently called on Putin to launch a "pre-emptive strike" on Ukraine, was shot and killed in a special operation by the SBU in Moscow. It also reported that Oleg Popov, a deputy in the Luhansk People's Republic regional assembly, was killed in a car bombing orchestrated by the SBU in Luhansk city.

A Ukrainian court sentenced a Russian soldier in absentia to 15 years' imprisonment for shooting at civilians near Izium in June 2023, while a resident of Luhansk Oblast who was captured near Bilohorivka in May 2023 was sentenced to 12 years' imprisonment for joining a pro-Russian armed group.

The G7 announced that it would ban imports of Russian diamonds from 2024 as part of sanctions imposed against Russia for its invasion of Ukraine.

The US Senate blocked a funding bill that included aid for Ukraine, Israel and Taiwan, with every Republican senator voting against it.

Documents seen by Reuters revealed that Ukraine was requesting more weapons from the United States such as three types of drones, F/A-18 Hornets, C-17 Globemasters, C-130J Super Herculess, AH-64 Apache and Black Hawk helicopters, and THAAD air defence systems.

7 December One person was killed in an overnight Russian drone attack on the port of Izmail.

Ukrainian actor was announced to have died from injuries sustained while fighting on the front in September.

Russian-installed authorities announced that they would start a "voluntary" evacuation of Nova Kakhovka on 13 December, citing the town's proximity to the fighting in the east bank of the Dnipro River.

Ukraine imposed sanctions on 300 individuals and entities linked to Russia. Among those sanctioned were Apti Alaudinov, the commander of the Chechen Akhmat battalion fighting in Ukraine, Ramzan Tsitsulayev, former special envoy of Chechen leader Ramzan Kadyrov to Ukraine, Midhat Shagiakhmetov, deputy prime minister of Tatarstan, and Adil Shirinov, CEO of the Ulyanovsk Automobile Plant.

Russian authorities claimed to have arrested a Belarusian national who was accused of bombing two trains on the Baikal-Amur Mainline on behalf of Ukrainian intelligence on 29–30 November. Two other individuals, including a former soldier were also arrested on suspicion of organizing arson attacks, spying on behalf of Ukraine and sending money to the Ukrainian military.

A court in Chernihiv Oblast sentenced a Russian soldier to 12 years' imprisonment for abducting and taking hostage a 15-year old for four days in 2022 in an effort to coerce his mother, a soldier, to give intelligence on Ukrainian positions.

8 December One person was killed in a Russian missile attack on Pavlohrad Raion, Dnipropetrovsk Oblast.

The SBU announced that a former director of a state-owned defense company and three others were charged with trying to embezzle Hr 3.9 million ($106,500) in funds used to procure Su-27 aircraft parts.

Germany delivered a military aid package to Ukraine that included 11 reconnaissance drones, six border protection vehicles, eight off-road Zetros trucks, 100,000 first aid kits and other medical materials, 33 GMG automatic grenade launchers, and additional 155 mm artillery shells.

The International Olympic Committee allowed Russian and Belarusian athletes to compete as neutrals in the 2024 Summer Games in Paris, in a decision that was criticized by both Russia and Ukraine.

9 December Two people were killed in a Russian missile attack in Kupiansk. One person was killed in a Russian drone attack on Beryslav, Kherson Oblast.

11 December

The Ukrainian Air Force claimed to have downed eight ballistic missiles and 18 drones overnight. One person suffered shrapnel wounds and three others suffered acute reactions to stress in Kyiv. An unfinished apartment building was also damaged.

One person was killed by Russian shelling in Kherson.

The UK government announced the transfer to Ukraine of two Sandown class minehunters from the Royal Navy.

The International Monetary Fund authorised a $900 million disbursement to Ukraine from its loan program.

Slovak truckers began blockading the Slovakia–Ukraine border demanding that the EU restore entry restrictions on Ukrainian trucking firms that were removed following the Russian invasion.

12 December One person was killed in a Russian drone strike on Odesa.

Russian air defences reportedly shot down a Ukrainian Tochka-U missile over Belgorod Oblast.

A "massive" cyberattack caused disruptions at Ukraine's largest mobile phone operator Kyivstar, and Monobank, one of the country's biggest banks. Authorities reported that the attack also disabled air raid warning systems in Kyiv Oblast, Sumy and Dnipro. The Russian hacker group Solntsepek, which is believed by Ukraine to be run by Russian military intelligence, subsequently claimed responsibility for the attack.

The HUR said that its cyber units, along with the Ukrainian Defence Ministry, hacked into the central server of the Federal Tax Service of Russia, as well as 2,300 of its regional servers, extracting sensitive information and destroying the entire tax database with malware.

During President Zelenskyy's meeting with US President Joe Biden at the White House, the latter announced a new aid package to Ukraine valued at $200 million.

Finland announced that it would double its manufacture of artillery shells, both for domestic defence and to ensure supplies to Ukraine.

13 December

Ukrainian officials said Kyiv was targeted by an overnight Russian air attack. About 53 people were injured, while a hospital and several buildings were damaged. Ukraine claimed it had downed all 20 missiles and drones launched.

Russia placed the head of the HUR, Kyrylo Budanov, on its wanted list.

14 December One person was killed in a Russian missile attack in Kherson Oblast.

The UK Ministry of Defence assessed that the Russian 104th Guards Airborne Division likely suffered "exceptionally heavy losses" during its first combat deployment against Ukrainian forces near Krynky.

Romanian authorities said that the remains of a Russian drone were found on its territory near Grindu, around 20 kilometres from the Ukrainian port of Reni. The drone was believed to have been launched over the previous night heading for targets in Odesa Oblast.

In Russia, nine drones were reportedly shot down over Kaluga and Moscow Oblasts.