Several attempts have been made to broker ceasefires in the Syrian Civil War.
First partial ceasefire (26 February – July 2016)
Following talks in Munich, the world powers in the International Syria Support Group negotiated a ceasefire between the main parties to the war. On 22 February 2016 the United States and Russia announced the Terms for a Cessation of Hostilities in Syria, pledging "that the cessation of hostilities will be monitored in an impartial and transparent manner and with broad media coverage." On 26 February 2016, the United Nations Security Council unanimously adopted resolution 2268 that demanded all parties to comply with the terms of a U.S.-Russian deal on a "cessation of hostilities". The cease-fire started on 27 February 2016 at 00:00 (Damascus time). The ceasefire does not include attacks on UN-designated terrorist organizations such as the Islamic State of Iraq and the Levant and the al-Nusra Front. At the close of February 2016, despite individual clashes, the truce was reported to hold.
In early February 2016, the formal start of the UN-mediated Geneva Syria peace talks and the opposition's protestations notwithstanding, the Syrian government carried on with its offensive operations in the Aleppo Governorate amidst speculations that Turkey, as well as Saudi Arabia and the United Arab Emirates, were preparing a military incursion into Syria. The Saudi announcement was welcomed by the United States. Responding to the calls for Russia to stop bombing opposition forces in Syria now that the peace talks had started, Sergey Lavrov speaking in Muscat, Oman, said Russia would not stop its air strikes until Russia defeated "such terrorist organisations as Jabhat al-Nusra and ISIL″; he also stressed the imperative that Syria's border with Turkey be secured to prevent smuggling and the movement of militants. Syria′s deputy prime minister Walid Muallem said that any foreign country′s ground intervention in the Syrian territory without the government's approval would be deemed an act of aggression to be confronted: "Any aggressor will be sent back to their country in wooden boxes, whether they be Saudis or Turks."
On 11 February, it was confirmed that the Syrian Democratic Forces based in the town of Afrin, north-west of Aleppo, had taken a series of towns, including Deir Jamal and al-Qamiya, as well as a former Menagh Military Airbase near the border with Turkey, previously taken by rebels. In retaliation, on 13 February Turkey began a sustained campaign of shelling on SDF positions in the area of Azaz from its territory.
On 14 March 2016, Russian president Vladimir Putin announced that Russia would be pulling out the "main part" of its military in Syria. Putin also said that Russia's Khmeimim airbase will be kept to control the ceasefire agreements and that its port at Tartus would continue to operate as normal.
According to Western sources, Iran has kept only 700 IRGC advisors in Syria after the ceasefire, but this has not been confirmed. In mid-March, the Ground Forces of Islamic Republic of Iran Army indicated it would send Army commandos and snipers as military advisers to Syria and Iraq, the first formal acknowledgement by Iran of deployment of regular Iranian Army (as opposed to IRGC) forces outside Iran since the Iran–Iraq War of the 1980s.
Syrian government with support from Russian and Iranian forces successfully captured Palmyra from the ISIL by the end of March 2016.
FSA and allied Islamist groups captured al-Ra'i from ISIS on April 8. The capture of the town secured an important supply line for the rebels from Turkey near whose border the town is located. ISIL recaptured the town along with six villages on April 11.
By July 2016, this ceasefire had mostly unraveled and violence again escalated.
Second ceasefire attempt (12 September – 19 September)
On 10 September 2016, Russia and U.S. reached a deal on establishing a cease fire between the Syrian Assad government and a US-supported coalition of so-called 'mainstream Syrian opposition rebel groups'.
This ceasefire was backed by the United States and Russia, with the understanding that – if it held for one week – Russia and the United States could begin to plan a joint mission against ISIS and al-Nusra. A notable loophole in the ceasefire meant that it did not apply to attacks against "terrorist targets" – the Russian government has used claims that it was targeting terrorist elements to justify airstrikes against rebel-held areas. The ceasefire went into effect on 12 September, but was poorly adhered to, with the Syrian government continuing bombing and UN humanitarian aid delayed by security concerns and the danger to convoys.