The fall of eastern Aleppo to the Syrian army and its allies is a turning point in the protracted civil war, and the wider proxy war.
Regime loyalists and supporters have dealt a decisive blow to the wide range of insurgents and their external sponsors: Turkey, Saudi Arabia, the Gulf emirates, the US, and Europe.
Damascus, Moscow, Tehran and Baghdad have reason to celebrate: 80 per cent of Syrians still living in Syria and the country's five major cities – Damascus, Homs, Hama, Latakia and Aleppo – are under government control.
However, the recapture by Islamic State of the ancient city of Palmyra at the height of the Aleppo offensive demonstrates that the war has not ended and the Syrian army and its partners have a long struggle ahead of them.
Their staying power will continue to be tested.
The first external force to intervene in the Syrian conflict on the government side was the military wing of the Lebanese Hizbullah movement which, in 2012, deployed fighters to protect, from Sunni radicals, the Shia shrine of Sayyida Zeinab east of Damascus.
Hizbullah joined the Syrian army’s campaign to clear insurgents from the Syrian-Lebanese border towns and took part in the liberation from al-Qaeda’s Jabhat al-Nusra of the Christian town of Maaloula in April 2014.
Since then, Hizbullah fighters have been involved in operations across Syria, with more than 1,500 of them killed in the process.
Alienated
Having driven Israeli forces from southern Lebanon in 2000 and 2006, Hizbullah has enjoyed the support of Syria, as well as Iran, since the movement's founding in the 1980s.
It has joined battle in the Syrian conflict with the aim of preventing insurgents from crossing into Lebanon and expanding the war westwards.
Iraq's Asa'ib Ahl al-Haq militia and Badr Organisation, both closely tied to Iran, have also contributed fighters to defend the Sayyida Zeinab mosque and expanded their deployments in order to reinforce the Syrian army on other fronts.
Iraq has opened its air space to Iranian flights carrying reinforcements, weapons and aid to Syria.
Baghdad’s Shia fundamentalist-dominated regime vehemently opposes the presence in Syria of Sunni radicals, particularly those belonging to Nusra and Islamic State, which have subverted Iraqi Sunnis alienated by their marginalisation and persecution by Baghdad.
Iran began its involvement in the war by dispatching advisers and trainers to the Syrian army, eventually deploying Iranian troops as well as Pakistani and Afghan expatriate recruits with combat experience.
There have been 1,100 fatalities among these forces, with 360 being Iranian nationals.
General Qassem Soleimani, commander of the Revolutionary Guards’s elite Quds Force, has spent time in Damascus helping to direct military operations.
Iran has air-lifted weapons and ammunition to Syria and provided fuel for power stations and vehicles.
Bitter rivalry
Iran enlisted Syria as its sole Arab ally in 1980 after the eruption of the eight-year Iran-Iraq war.
Damascus was motivated to take Tehran's side in this conflict by the bitter rivalry between the Syrian and Iraqi wings of the Baath party and by the 1979 peace agreement between Israel and Egypt, which removed the largest Arab army from the military front against Israel, undermining Arab deterrence.
The alliance has endured and turned Arab and western powers against the Syrian government.
Even though the agreement on the dismantling of Iran’s nuclear programme in exchange for the lifting of sanctions has eased western hostility towards Tehran, the antagonism toward Damascus remains.
While Lebanon, Iraq and Iran had provided much-needed boots on the ground, the belated intervention of the Russian air force in September 2015 bolstered pro-government forces' ability to resist attacks and reclaim lost territory from insurgents who, in March 2015, seized the northwestern Idlib province and menaced the coastal cities.
Idlib is likely to be the next focus of the pro-government camp.
Russia inherited from the Soviet Union a long-standing relationship with Syria and the Assad family.
During the cold war, Syria – although a member of the Non-Aligned Movement – tilted towards Russia due to its stand against Israel’s occupation of Palestinian territory and its confrontation with the US and former western colonial powers.
By providing military training and arms for Syria, Egypt and Iraq, the Soviet bloc projected power in the region, won allies and made enemies.
Russia’s current involvement in Syria has had the same result.
Moscow’s immediate aim is to contain Muslim radicalism on the international, regional and internal fronts.
Some 2,500 Russian nationals and 7,000 from the former Soviet bloc have been fighting with Islamic State in Syria and Iraq.
Several thousand have returned home and could pose a security threat to Russia and surrounding countries.
Having faded as an international player since the fall of the Soviet Union, Russia is also determined to regain lost influence and challenge the US and Europe in a region Moscow considers its backyard.