As William Hague meets EU foreign ministers today, he should be asking both is it legal, and is it advisable to send arms to Syria's rebels.
How would the Government prevent British-supplied weapons falling into the wrong hands, and how does supplying weapons help to secure a lasting peace?
Syria today is awash with arms and in the House of Commons last week MPs on all sides expressed real concern about the identity, intent and tactics of some of the rebel forces.
In Washington the Prime Minister clearly failed to convince president Obama of his case, so today in Brussels the UK's use of the veto would confirm that the Prime Minister had also failed to convince our European partners.
Fears are growing of an arms race in Syria after EU countries agreed they could arm rebels while Russia could give missiles to the regime.
Foreign Secretary William Hague said a "clear message" had been sent to Assad's regime after the EU decided to lift the Syrian arms embargo.