"Once we take action, we should be prepared for what comes next. Deeper involvement is hard to avoid," General Martin Dempsey, the chairman of the Joint Chiefs of Staff, wrote one month ago. His letter to Congress was an exercise in damping speculation about involvement in Syria. If it was written to pour large quantities of cold water over all military options, today Gen Dempsey no longer has that luxury, with an airstrike which may be within days of being launched. Nor are the questions that he raised – and that his British counterparts are raising in private – academic or an exercise. They are, though, no closer to being answered. What is the strategy behind an airstrike on Bashar al-Assad's command and control centres? What would a "limited action for a specific purpose" achieve? What would "limited" mean, if the specific purpose – stopping the use of chemical weapons in Syria – were not achieved?
After eight western interventions in Arab or Muslim countries in 15 years, sceptical generals and a hostile western public at large are entitled to answers. They are surely entitled to demand clarity from their political leaders, not least because the consequences, unintended or otherwise, of previous interventions show little sign of abating. Specifically in Syria, the most toxic and enduring element of the civil war – the sectarian battle between Sunnis and Shias – though a historic one, is a product of the way US forces used Shia militia when they first came under sustained attack from Sunni insurgents in Iraq. Syria is so intractable not just because of where it is, and who its neighbours are, but because the damage caused by such interventions is cumulative.
The consequences of an airstrike, under which Mr Assad's forces would not noticeably buckle, could be far-reaching. After a civil war that is killing 5,000 every month and has created 1.8 million refugees, straining to the limits the resources of neighbouring countries, the primary objective of all regional powers has got to be to stop it. It was clear a year ago that Mr Assad's departure could no longer be used as precondition for talks over a transitional government, but the attempts to reconvene peace talks in Geneva stumbled primarily because no rebel side of negotiators could be convened who acknowledged this truth. If anything, Mr Assad's military and thus his negotiating position today is stronger. For much of the time, the rebel leadership has argued for one more push and the house of cards that Mr Assad is standing on will fall. That is less likely today than it ever was. And the house of cards looks more like a concrete bunker. Neither defections, nor better weapons, may now dislodge him. But each could push back the day further when serious talks start in Geneva. An airstrike could also give the rebels the impression that if the US could be prevailed upon to strike once, they could be called upon to strike again. Hence Gen Dempsey's question of where this ends.
The return to Geneva has to involve Russia and Iran, both of whom have acknowledged that chemical weapons have been used in Syria but blame their use on jihadi groups fighting on the rebel side. Before the moderate credentials of Iran's new president have even been tested at the negotiating table with the US, Hassan Rouhani is coming under pressure from parliamentarians and Iranian commanders urging a retaliatory attack on Israel. They see Syria as the first trench of their defences.
Iran has a terrible collective experience of chemical weapons used by Saddam Hussein in the Iran-Iraq war, to which the US and Britain, who were at that time backing the Iraqi dictator, turned a blind eye. If the process of trying to prevent the use of chemical weapons in Syria was kept within the framework of the UN, or if, as the price of avoiding an airstrike, Iran could back the idea of a permanent UN presence in Syria monitoring Mr Assad's stocks of chemical weapons, then a way back to the negotiating table could be found. This is a slim hope. More likely, waves of cruise missiles could soon be heading towards Syria to feed a fire that is already well lit.