Obama had repeatedly drawn a "red line" on the use of chemical weapons by the Syrian regime, warning President Bashar al-Assad that using or moving chemical stockpiles was the one thing that would " change my calculus" on that war.
Israel has said it wants to stay out of the brutal Syria war, but could inadvertently be drawn in as it tries to bolster its deterrence and prevent sophisticated weapons from reaching Hezbollah.
Mr Barnier suggests lengthening the list of Petersberg tasks (so named for the German town where they were drawn up), to take account of the heightened risk of global terrorism and non-conventional weapons.