A year ago there might have been some logic in arming the Syrian rebels in their efforts to overthrow the brutal regime of Bashar al-Assad.

But what began as Syria's response to the Arab Spring now has morphed into an increasingly bitter and brutal sectarian war, with atrocities ascribed to both sides, including the sporadic use of chemical weapons.

Yesterday UK Foreign Secretary William Hague made it clear that having put paid to the EU arms embargo on Monday, he does not feel constrained to wait until August before sanctioning arms shipments, even if initially he wants to focus on the peace talks planned for June.

He hopes the mere threat of arming the rebels will be enough to bring the Assad regime to the table and extract significant concessions. This is unlikely. President Assad regards this conflict not only as an existential threat but a war that he can win and recent events have encouraged him.

The UK and French governments want to arm the "good rebels" (the Free Syrian Army as opposed to the confused mass of jihadist factions that are now lining up on their side) but this is easier said than done. Yesterday Mr Hague declined to say which weapons would be sent. Modern weaponry is increasingly complex and those using them need to be trained. That would involve sending into the war zone personnel who would be targets for Syrian government forces and Hezbollah.

Besides, how would arms get into Syria without falling into the hands of either Syrian government forces or al Qaeda-linked extremists? Menzies Campbell, who has been asking some of these "daft laddie" questions, raises the spectre of Afghanistan, where Nato forces came up against some of the prodigious quantity of military hardware that the US had once supplied to the Mujahideen to help them resist the Russians.

There are also serious doubts about the legality of arming the Syrian rebels under the terms of the new international Arms Trade Treaty, passed by the UN in April. This states that arms transfers cannot be authorised where there is a major risk that they will be used to violate human rights and international humanitarian law.

Fears that ending the EU embargo would merely ramp up the Russian response looked justified yesterday. After delivering shore-to-ship missiles to the Syrian government last week, the Kremlin announced it would be sending anti-aircraft missiles too. Clearly, these are not for immediate use against the rebels, as the latter have no aircraft, but they are a statement of intent in the event of a naval blockade or an attempt to establish a no-fly zone. Thus the conflict escalates.

The Foreign Office is said to be dubious about sending arms to Syria. And voices urging caution are coming from right across the political spectrum from John Redwood to Douglas Alexander. They should be heeded. Rather than indulging in an arms war with the Russians, UK efforts should focus on supporting Turkey, Lebanon and Jordan with the millions of refugees and pressing on with diplomacy. Call it the least worst option.