Both Russian and Ukrainian military observers have told the OSCE that an unidentified “third party” is provoking the two sides
RI Staff 
1 hour ago | 51 Comments Tweet
What to make of this? Via OSCE:
At the Joint Centre for Control and Co-ordination (JCCC) observation point at Donetsk railway station (“Donetsk People’s Republic”-controlled, 8km northwest of Donetsk city centre) the SMM witnessed attempts by the JCCC to organise three ceasefires (to begin at 08:50hrs, 09:30hrs and 11:00hrs respectively) flounder as sporadic firing of mortars and machine guns started within a few minutes of the arranged start time. According to both Ukrainian Armed Forces and Russian Federation Armed Forces officers at the observation point, an unidentified “third party” was provoking the two sides. The Ukrainian Armed Forces and Russian Federation Armed Forces officers informed the SMM that they had negotiated a fourth ceasefire which the SMM observed being respected from 13:07 to 15:37hrs.
Cui bono?