The following is a timeline of the Syrian civil war for 2021. Information about aggregated casualty counts is found at Casualties of the Syrian civil war.

January

On 1 January 2021, the UK-based Syrian Observatory for Human Rights (SOHR) reported that a bomb exploded near a Russian military base in the Tal Saman area south of Ayn Issa, wounding several Russian soldiers. Prior to the blast, SOHR said an explosives-laden pickup truck was parked just outside the Russian base by two men who then fled the area. Guardians of Religion Organization claimed responsibility for the attack through a message circulated on social media. SOHR's Rami Abdel Rahman described it as "the first such direct attack against a Russian base in northeastern Syria".

On 3 January, three buses were attacked by suspected Islamic State militants on a highway in central Syria, leading to the death of nine people. According to state sources, the dead included a thirteen-year-old girl, with four others injured, while SOHR said seven of the dead were soldiers and there were 16 wounded, and local sources nine military deaths. The Jerusalem Post reported that Western intelligence sources linked the rise in militancy to local Arab Sunni tribal anger at executions for suspected IS ties of dozens of local nomads by Iranian Shi'ite militia in the area.

On the night of 6 January, according to SOHR, Israeli airstrikes left three Iran-backed militia dead.

On 9 January, according to SOHR, IS insurgents attacked pro-government soldiers in the town of Al-Shola, in the Deir ez-Zor Governorate, during a sweeping operation looking for jihadist cells. The attack left at least 7 National Defence Forces militiamen dead and an unknown number wounded.

On 11 January, Syrian army forces and allies infiltrated and raided Army of Victory positions in Al-Ghab Plain, northwestern Hama, killing 11 fighters of the rebel group.

On 13 January, Israeli air strikes were allegedly launched in eastern Syria, close to the Iraqi border, according to the SOHR. Apart from the strike being carried out close to the Syria-Iraq border, it was also reported that it had hit sites in eastern Syria's Deir Ezzor region as well. At least 18 strikes were launched across multiple locations in eastern Syria, the organization added. According to France 24, at least seven Syrian soldiers and 16 allied fighters were killed during the Israeli raid over night. Later in the day, it was reported by the SOHR that the death toll had reached fifty-seven people, while 37 others were injured, with some sustaining critical injuries. However, the airstrikes that were carried out by Israel against Iranian-backed targets, were believed to have been executed with intelligence given by the United States, a senior US intelligence official disclosed.

Also on 13 January, there were clashes in Tafas in the western Daraa countryside, between the rival Zoubi and Kiwan clans, leading to the deaths of four people from both sides.

On 14 January, SOHR reported that Liwa Fajr al-Islam rebel fighters captured three government fighters in the western Daraa countryside, as part of a renewed rebel offensive.

On 18 January, according to the Israeli Meir Amit Intelligence and Terrorism Information Center, IS militants fired machine guns at Syrian soldiers east of Hama. Six soldiers were killed.

On 22 January, the state-run SANA news agency claimed that Israel launched a fresh missile strike that hit central Syria's Hama province. The Syrian government said at least four family members were killed during the attack, including two children, with four others injured. However, the Syrian military maintained that its air defense systems managed to intercept most of the Israeli missiles. There was no immediate comment from Israel regarding the incident.

On 23 January, government 4th Division fighters launched a new offensive in the western countryside of Daraa, targeting the towns of Tafas, Muzayrib and Al-Yadudah. On 24 January, SOHR reported that negotiations broke down between pro-government forces and rebel factions (in particular Fajr al-Islam and the Central Committee), resulting in clashes in the cities of Tafas and Muzayrib. Several rebel fighters were killed and at least 4 members of the 4th Division were confirmed to have died, according to the Syrian Observatory. Rebels attacked 4th Armoured Division checkpoints north of Saham al-Jawlan in the Daraa countryside and on the Nafia-al-Shajara road in the Yarmouk Basin.

Also on 24 January, IS militants targeted a Syrian army bus on the road between Palmyra and Deir ez-Zor. At least 12 Syrian soldiers were killed according to SOHR. Although the Islamic State (IS) militants have been blamed, no group has officially claimed responsibility for the attack yet, according to GardaWorld.

On 25 January, as reported by SOHR, in Al-Mayadeen, 13 ISIS members were killed by Russian airstrikes. In addition ~17 Fajr Al-Islam members and 4 Syrian militia members were killed in the clashes. The Russian military is acting as a mediator in these events, and has threatened a military incursion if compliance is not given.

On 26 January, according to SOHR, Syrian government forces and IS militants clashed in the Homs desert, leaving at least 7 pro-government fighters and 11 IS militants dead.

On 29 January, the Syrian government rejected UN proposals as part of constitutional talks to resolve the Civil War.

30–31 January saw a weekend of violence in Northwest Syria.

On 30 January, a car bomb in Turkish-controlled Afrin, killed eight, including four children; SDF/PKK forces were believed responsible. According to SOHR, four NDF militiamen were killed by an IS landmine in the Syrian desert. Forces of the Syrian army's 5th Corps came under attack by IS militants east of Homs, resulting in the death of at least one officer and several other soldiers according to Halab Today TV. Also on 30 January, according to SOHR, a car-bomb exploded in the Turkish proxy held town of Afrin, killing at least 8 and injuring several others.

On 31 January, 11 people were killed in two separate car-bomb attacks in the cities of Azaz and Bizaah (just outside Al-Bab) in the Turkish-backed SNA-held area of Northern Syria. The attack in Azaz was near a building used by SNA fighters. Turkish officials have blamed the attack on the SDF. Five Turkish-backed fighters died in the attack in Bizaah.

Meanwhile, in Syria's northeastern city of Hassakeh, Deir Ez Zor province, one person was reportedly killed and four others injured, when Syrian Democratic Forces (SDF) shot at pro-government protesters. The protesters were demonstrating against the siege on their neighborhood in Hassakeh city, as dozens of men were seen taking to the streets. According to Kurdish sources, though, the incident occurred as pro-government forces attacked an SDF security point, leading to the death of one government fighter, while the Turkish Daily Sabah reported that the Syrian who died was a regime security member killed by the YPG forces after they had opened fire on pro-Assad protesters.

Also on the 31st, according to SOHR, several military formations the Peace Spring area of NW Syria, under the banner of Ahrar al-Sham, stated they had suspended operation. The statement was issued by the groups "Liwaa Al-Qadisiyah" (which had previously operated under the banner of IS), "Liwaa Al-Khattabe", "Liwaa Suqur Al-Sunnah", and "Liwaa Ahl Al-Athar".

February

On 1 February, an IS IED was activated against an SDF vehicle in central Al-Raqqah. One fighter was killed and another was wounded.

In February, IS operatives fired at an SDF fighter in the Al-Basira area, about 25 km southeast of Deir ez-Zor. The fighter was killed. In addition, a member of the SDF civilian council in the Al-Basira area was targeted by machine gun fire about 15 km north of Al-Mayadeen. He was killed.

On 2 February, a truce between SDF forces and government forces lifted a three-week SDF siege of government-held neighbourhoods in Kurdish-controlled Hasaka and Qamishli. The same day as reported that the Syrian government announced that any man (including displaced people) who did not do military service before the age of 43 must pay $8,000 or lose their property without notice or any right to appeal.

On 3 February, SOHT reported that a Turkish soldier died of wounds sustained in an attack on 31 January by unnamed gunmen. Also on 3 February, IS launched an attack on Syrian forces in Hama province, killing 19 regime personnel including 11 fighters of the Iranian-backed Baqir Brigade according to SOHR. Since March 2019, the death toll of regime personnel and allied militia forces as a result of IS attacks has now reached at least 1,200, the Observatory reported.

A suspected IS VIED targeted a pro-government checkpoint near the Al-Maleha area, south of Deir Ez Zor. The attack left over 10 members of Liwa Al-Quds and the Syrian Army's 17th division dead and others wounded. Exchange of heavy fire was also reported between the IS members and regime fighters. Separately, the SDF disclosed that during operations this week, it had apprehended four suspected members of the Islamic State (IS) in Deir al-Zor and Hasakah provinces of Syria.

Also on 3 February, airstrikes by Israel. An official speaking on the condition of anonymity maintained that the Israeli missiles were launched from over the Golan Heights, without disclosing what the actual target was. No casualties were recorded during the attack, only material damages were said to have been caused, according to The Jerusalem Post. However, the SANA state news agency cited a military source who maintained that the Syrian anti-air defenses were able to intercept most of the Israeli missiles. An SDF intelligence operative was targeted by gunfire in the Diban area, about 5 km east of Al-Mayadeen. He was killed.

On 4 February, according to SOHR, a Turkish officer was killed while he was dismantling an IED that was intended to detonate at the entrance to the headquarters of "al-Hamza Division". The same day was also reported that IS operatives attacked Syrian army positions near the Al-Taym oil field, leaving 3 special forces of the Syrian army and air force dead.

On 5 February, according to SOHR, four Syrian soldiers of the 17th Division were killed and six others were injured, after IS cells attacked them while they were combing Al-Tayarat area in Al-Mayadeen desert. The same day according to SOHR, eight jihadists of the Turkistan Islamic Party (TIP) were killed, as government forces targeted their bus by a guided missile on Kherbet Al-Naqous frontlines in Sahl Al-Ghab in the western countryside of Hama.

On 6 February, according to SOHR, four government soldiers were killed, including a lieutenant, while eight others were injured as a result of a Jaysh al-Nasr surprise attack in the village of Al-Fatirah in western countryside of Hama. Also on 6 February, an SDF vehicle was targeted by machine gun fire in Shahil, about 10 km north of Al-Mayadeen. One SDF fighter was killed and another was wounded. IS operatives also captured an SDF intelligence operative in the Basira area, about 15 km north of Al-Mayadeen. He was interrogated and then executed.

On 7 February, according to SOHR, government forces and loyal militias launched an attack in the early hours of Sunday morning on positions of the TIP on Al-Haloubi and Al-Ankawi frontlines in Sahl Al-Ghab. The TIP repelled the attack; five government soldiers were killed and at least nine others were injured, while TIP lost three fighters and others injured. Two other government soldiers, including a lieutenant, were also killed by sniper fire in a separate incident, according to SOHR. Also on 7 February, an SDF fighter was targeted by gunfire in the village of Shahabat, in the eastern rural area of Deir ez-Zor. He was killed.