ANTONIO GUTERRES is a man of experience. A former prime minister of Portugal, he has run the UN’s High Commission for Refugees since 2005, dealing with crises from Afghanistan to Congo and Iraq. But of all the humanitarian catastrophes he has witnessed, nothing has proven as appalling or as dangerous as what is happening in Syria. “This is the most brutal, even with very brutal conflicts elsewhere,” Mr Guterres has said. “If one looks at the impact on the population, or the percentage of the total population in need, I have no doubt that since the end of the Cold War it is the worst,” he told the Guardian, a British newspaper. “And it will become even worse still if there is no solution. My belief is that if we take all of these elements, then this is the most dramatic humanitarian crisis that we have ever faced. Then if we look at the geopolitical implications, I have no doubt that this is the most serious that we have ever dealt with.”

It is hard to argue with that. The two-year-long civil war has left at least 70,000 dead and displaced nearly a quarter of the country’s 23m people. Mr Guterres estimates that, at the current rate, the number of Syrians in need of humanitarian aid, now 6.8m people, could exceed 10m by the end of the year. The number of Syrian refugees in neighbouring countries is likely to double to 3m.

It is hard to discern any glimmer of light at the end of the tunnel. Western and Arab leaders who met in Istanbul on April 20th promised more help for the rebels, including a doubling of American funds for “non-lethal” aid to $250m. But on the ground, after a winter of small, steady advances by rebels, the regime’s forces seem to have launched some brutal counter-offensives. In a single recent sally by government forces south-west of the capital, Damascus, some 250 people, nearly all civilians, are said to have been killed, according to unconfirmed reports by local “revolutionary committees”. Ominously, too, a senior Israeli intelligence official revealed on April 23rd an assessment that the Syrian regime has used chemical weapons, most likely sarin, a nerve gas, “on a number of occasions in the past few months.”

The degeneration of what started as a peaceful, broad-based popular uprising into a vicious sectarian war continues apace. A recent declaration of allegiance to al-Qaeda by one of the most disciplined and successful rebel groups, Jabhat al-Nusra, confirms a tilt towards Islamist extremism among Syria’s Sunnis, who make up three-quarters of the population and have borne a disproportionate toll of the fighting. The danger of the country’s misery infecting the wider region was also highlighted when several prominent Sunni religious leaders in neighbouring Lebanon issued a joint fatwa calling for jihad in Syria. This came in response to the growing involvement of Hizbullah, the Lebanese Shia party-cum-militia, in fighting on the side of the Syrian regime. Meanwhile, unidentified gunmen abducted two senior Christian clerics on April 22nd, the Syrian Orthodox and Greek Orthodox archbishops of Aleppo.