The US-led coalition scrambled fighters after Syrian regime jets targeted Kurdish forces working with US advisers in northern Syrian, an incident marking another escalation in Syria's bloody conflict, the Pentagon said Friday. Thursday's air strike, conducted by two Syrian SU-24 attack planes, targeted Kurdish forces who were undergoing training from US special operations advisers in the area around the north-eastern city of Hasakeh, Pentagon spokesman Captain Jeff Davis said.

"This was done as a measure to protect coalition forces," Davis said. "We will ensure their safety and the Syrian regime would be well-advised not to do things that place them at risk... We view instances that place the coalition at risk with utmost seriousness and we do have the inherent right of self defence."

Copyright Agence France-Presse, 2016