Collision course: Turkey warns Syria over Russia-backed Idlib offensive

It's a grim endgame in northwest Syria. There are daily killings, sometimes by the dozens, plus up to half a million people displaced as the Russian-backed forces of Bashar al-Assad intensify their offensive against the last rebel-held province. The writing had long been on the wall after Assad agreed to turn Idlib into a giant holding pen for besieged rebels from elsewhere. Is this merely the start of another dark chapter?