The battlefields of Syria are now more complex than they have been at any point during the civil war. With plans for a second Geneva peace conference again percolating, it remains unclear who the anti-Assad opposition might send, or who they might claim to represent.

Ground into what even Syria's deputy prime minister Qadri Jamil admits is a stalemate, and lured towards an increasingly violent standoff with jihadist groups, Syria's moderate or mainstream armed opposition have had few wins lately. Two and a half years into the war, the common ground staked out at the start is now a bitterly contested field of competing interests that seriously imperil the opposition's reason for taking up arms in the first place.

More than 1,000 units now make up the anti-Assad forces, and while many can still unite behind the stated common cause of ousting the president, many others show no such discipline or even a will to work towards a pluralistic, democratic society if, or when, the Syrian leader falls.

Things are no less complex on the regime side. The standing Syrian military has been supplemented by a home defence force, the clout of Hezbollah and a large number of Shia fighters from outside Syria who have increasingly taken positions at the vanguard of the fighting.

This year, northern Syria has seen a steady and significant shift in the groups lining up against the regime and in the influence that they bring to the battle. Every month since the beginning of Ramadan in July 2012, jihadist groups have increased in numbers and prominence. The regime has lost significant ground here which it is unable to retake.

Jabhat al-Nusra was the standard bearer of the early days of the jihadist insurgency and by November 2012 it was either jointly leading operations with mainstream groups or taking the outright lead on many of the battles fought for the north.

By early this year, its ranks had been swelled by foreign jihadists who had flocked to Syria – many of them through Turkey. The foreigners called themselves al-Muhajirin, and by March had started to form their own units in the Aleppo and Idlib countryside, as well as in the Jebel al-Krud plateau north of Latakia and in eastern Syria, where the oilfields proved attractive, as did the corridor to Anbar in Iraq, where a rejuvenated al-Qaida insurgency is again wreaking havoc.

In May, the potency of Iraq's born-again jihad made its way to Syria, with a group loyal to the leader of the Islamic State of Iraq, Abu Bakr al-Baghdadi, breaking away from al-Nusra and later subsuming the group in much of the north. The new group, which calls itself the Islamic State of Iraq in Syria, has taken a more hardline stance than even al-Nusra, clashing with units aligned to the Free Syrian Army and attempting to impose its will on the societies that now reluctantly host its members.

All the while, mainstream units in the north have repeated the refrain that they cannot fight al-Qaida at the same time as they are struggling to defeat the regime.

In central Syria, jihadist groups do not have the same presence. The war around the cities of Homs and Hama is by and large a standoff between Free Syrian Army units, who are armed by a military council that reports to the Turkey-based Syrian civil opposition, and a regime that is slowly gaining ground with the help of its powerful backers.

Syria's Alawite minority communities are nearly all in the centre of the country. So too are Shia and Christian villages, which have remained loyal to Assad. The battle here matters greatly to the regime and to its key patron, Iran, with both determined to make sure that the heartland retains a contiguous link to the north-west coast and to the capital, Damascus, no matter what happens in the rest of the country.

In Damascus the regime retains control of the area that matters most to it – the central city that houses most government institutions, the presidential palace and the core of the security establishment.

Opposition attempts to make inroads into the power base have been unsuccessful. But rebels have remained firmly entrenched in the east of the city, despite repeated bombardments over many months and – according to the UN, Nato, much of Europe, the US and the Arab League – a chemical weapons attack carried out by the regime that killed more than 1,000 people.

While the regime is not losing the capital, it is not winning it either. Its gains in the centre have been offset by losses in the north that have put Aleppo and the oilfields out of its reach. Despite Assad's claims of sweeping battlefield gains, his deputy prime minister has a more realistic take on things; the civil war seems unwinnable for either side.