The British government's stance that led to the end of the EU’s arms embargo on Syria is based on flawed logic and will likely exacerbate and prolong the civil war. In an acrimonious meeting of European ministers in Brussels on Monday, Britain, supported by France but opposed by all 25 other EU member states, vetoed a move to extend the embargo, paving the way to send arms to the 'moderate' elements of the opposition.

The British government’s position, championed by UK Foreign Secretary William Hague, appears to be based on two calculations. Firstly, the reason given in public is to put pressure on President Assad to negotiate. Peace talks in Geneva between the regime and rebels are scheduled for next month and, while it is unclear if they will actually take place, Britain believes the stick of potentially arming the rebels could force Assad to compromise. Secondly, Britain is worried that the moderate rebels are rapidly losing ground to more radical and jihadist elements such as Al-Qaeda-affiliated Jubhat al-Nusra. If negotiations in Geneva get nowhere as many expect, beefing up the forces of Free Syria Army (FSA) commander Salam Idriss and others could tip the balance within the opposition against these radicals.

Yet both calculations are dubious. The threat of arming the rebels is unlikely to convince Assad to change his stance. Every time the rebels have made gains, the regime has been sent a vast supply of arms, financial support and even fighters from its key international allies Russia, Iran and Hezbollah. Assad knows they will match or exceed any new weapons sent to the rebels. Unsurprisingly, within hours of the EU decision, Russia announced it would go ahead with deliveries of S-300 anti-aircraft missiles to Syria to deter foreign intervention.

Assad has proved unwilling to compromise throughout the conflict, despite having lost half of his country to the rebels. His inner circle has similarly shown itself to be steadfastly loyal and the once-vaunted prospect of an internal coup against him has receded. As long as the regime retains the support of these foreign backers, who have proven far more committed to Assad’s survival than western states are to his removal, it is unlikely that a limited number of western arms will force any compromise within the regime. Moreover, the embargo was lifted in the face of considerable EU opposition and division which hardly convinces Assad that he is facing a united and determined Western front.

Arming the rebels is unlikely to strengthen the so-called moderates either. Jihadists such as Jubhat al-Nusra have succeeded not just because they are better armed, but because they are better organized, committed and have won popular support through distributing aid and eschewing the corruption that plagues FSA-affiliated militia. The FSA, which is more a collection of localized militia than a single organized unit, may benefit from weapons temporarily but the 'moderates' problems are far deeper than simply a lack of arms.

Britain’s policy is fraught with further risks. Weapons could end up in the wrong hands. While Hague insists recipients will be carefully vetted to ensure they are 'moderate', there is no guarantee they will not radicalize in the future. Moreover, with reports of jihadists clashing with moderates over oil resources and elsewhere, can Hague also guarantee that jihadists won’t simply steal the weapons from Britain’s allies? As Syria becomes a failed state and destabilizes its neighbours, might British and French-supplied anti-aircraft weapons soon be downing western passenger airliners across the region?

A further risk is that, irrespective of the impact on the regime, this move deters the opposition itself from negotiating. Britain has promised not to deliver any weapons until August, after the Geneva conference is due to take place, but the rebels may prove sceptical of its value knowing they are to receive western arms anyway. They, like Assad, don’t really believe in a negotiated solution and may now attend the conference as the price for western weapons rather than going to reach a deal.

Hague’s move ultimately represents Britain’s frustration at its inability to find a workable solution to the Syria crisis. This is the latest in a long line of unsuccessful moves, including economic sanctions and diplomatic action to try to force Assad from power. Yet the reality is that, given their unwillingness to commit their own forces, Britain, France and the US have less influence over the Syria conflict than they would like. With Saudi Arabia, Qatar, Turkey, Iran, Hezbollah and Russia all committing far more resources, western states are currently bit-parts in a much larger regional proxy war. Threatening to send the rebels western weapons may drag them further into the conflict but it is unlikely to change its course in the way Hague hopes. If anything it will prolong and expand it by prompting reciprocal arming from Assad’s allies.

Britain and France might wish to consider how much real influence they have left in this part of the world. They might be better to focus on goals that are within their power, for example, mobilizing the international community to help Syria’s 1.5 million refugees and 4 million internally displaced. Pushing international donors to honour their commitments and helping Syria’s overwhelmed neighbours in Lebanon and Jordan might prove a more effective use of Mr Hague’s energy.