As the Syrian conflict approaches its fourth year, the only participants with any cause for satisfaction are the ruling regime and the most extreme element of the opposition, the Al-Qaeda-affiliated Islamic State of Iraq and al-Sham (ISIS).

The regime’s success lies in its survival – achieved at an appallingly high human and material cost – and in having called US President Barack Obama’s bluff over the use of chemical weapons. ISIS and a cluster of marginally less extremist groups have exploited the weaknesses of opposition groups that looked to the West and Gulf Arab states for support, and have led a resurgence of the jihadist cause across northeastern Syria and western Iraq.

“Judging Al-Assad to be the lesser of two evils would be the crowning mistake [for opponents of his regime]”

For some of the world powers seeking to resolve Syria’s conflict, the prospect of a settlement in which President Bashar al-Assad remains in place no longer seems so outlandish. It would complement efforts to build on the detente in Western relations with Iran, and would allow for the creation of a common front against Al-Qaeda. However, any such shift from implicit acceptance of the reality of the Al-Assad regime’s durability to explicit engagement with a leader who has wrought such devastation on his country would be the ultimate betrayal of the Syrians who were encouraged by the West and by Arab leaders to rise up against their government.

Among the opposition’s supporters, Paris and Riyadh have taken the clearest position in rejecting deals that would leave Al-Assad in power. Even Moscow has endorsed the Geneva formula insisting on mutual consent on the formation of a transitional governing authority.

The opponents of the ruling regime have made several blunders and miscalculations since the uprising began in 2011. To fall into the trap of judging Al-Assad to be the lesser of two evils would be the crowning mistake.