Most people understand what is involved in a ceasefire.  Fewer would be familiar with the term 'cessation of hostilities', and there would not be many at all who would know what a  'regime of calm' means. This melange of terms reflects the challenges involved in brokering any kind of reduction in fighting in the confused and confusing environment that is Syria.

Syrian kids protest against Assad Regime forces air attacks targeting Aleppo

The confusing terminology largely reflects the fact that military action was allowed to continue against the two proscribed terrorist groups, Jabhat al-Nusra and Islamic State.  On the face of it, this sounded like an imperfect — but feasible — diplomatic outcome.  Syrian forces used the opportunity to shift their weight of effort to attack Islamic State targets and retake the symbolically important, and operationally useful city of Palmyra/Tadmur.  Coalition aircraft, both alone and in concert with Kurdish ground forces, have kept up the pressure against Islamic State in the northeast.

And while the 'cessation of hostilities' has more or less held and led to a reduction in deaths, a golden thread has started to unravel the cessation; Aleppo.  This is not only because Aleppo has been a strategic focus of the regime since the introduction of Russian airpower allowed Syrian and allied forces to resume offensive operations, but also due to the fact that Jabhat al-Nusra operates within it.

And therein lies the rub.  Unlike Islamic State, Jabhat al-Nusra has been a much more Syrian-focused group, and much more collaborative with on-the-ground partners.  It is far more respected by locals than is Islamic State, so groups regularly form local alliances and fight with it.  More respected doesn't mean wholly respected, as indicated by protests in Idlib, and concerns about the group's renewed interest in Aleppo reported by Lebanese media.   The more cooperative environment on the battlefield though means it can be difficult to separate Jabhat al-Nusra from other, non-proscribed groups.  The Russians and Syrians don't really care, and view anyone working with Jabhat al-Nusra as fair game.  The US and its allies think the Russians and Syrians overstate the areas within which Jabhat al-Nusra operates so they can take over more territory in Aleppo.  Hence the difficulty in reconciling areas that are fair game for targeting and those that aren't.  This dilemma has resulted in a rather extraordinary proposal; a joint Russian/US violation monitoring centre,  extraordinary in its concept and extraordinary if it works.    

With the Geneva peace talks currently moribund (Germany and France are trying to perform CPR), and the cessation of hostilities hanging on by its fingernails, Aleppo has become the last hope for the reduction of fighting to stay.  But, with a regime that sees Aleppo as 'winnable', Washington which has warned Damascus against thinking this, and an opposition who continues to cooperate with a proscribed terrorist group on parts of the battlefield, the prospects for anything other than a temporary respite to the fighting appears bleak.

Photo by Stringer/Anadolu Agency/Getty Images