There have been a number of claims, both from the ground in Syria and from media abroad, that Syrian government forces have been using white phosphorus (WP) munitions to target rebel positions or civilian populations. Unfortunately, these reports appear to be confusing the appearance of ZAB series cluster bomb submunitions (likely ZAB-2.5 submunitions) with that of certain WP munitions. To date, I have seen no evidence of WP use by either side in the Syrian conflict. Update16/12/2012: I have observed what is likely limited use of WP munitions in Syria. More here. Note that many sources are still misidentifying ZAB-2.5 subs (and possibly ZAB series conventional bombs) as WP.
This Al Jazeera report is typical of the claims of WP use I have seen to date. Note that the still image at the end of the report appears to show a WP munition, though this is likely a file photo. If someone knows this not to be the case, please get in touch with me.

