AFTER months of teetering, Lebanon's so-called government of national unity has tumbled. Sharply polarised between pro- and anti-Western camps, fragmented among religious sects and parties, and buffeted by the influence of rival foreign meddlers, the chronically troubled little country looks set to plunge into yet another swirl of turbulence. These often end in violence, drawing in outside powers and shaking the wider region.

The resignation of 11 ministers in the 30-member cabinet prompted the collapse. The opposition, known as March 8th and led by Hizbullah, the Iran-backed Shia party-cum-militia, had gained a blocking third of cabinet posts in 2008, after bloodying the Western-backed parliamentary majority in an armed showdown.

Installed as prime minister, Saad Hariri, leader of a pro-Western front known as March 14th, then invited March 8th into a government that pepped up the economy but failed to reconcile the starkly different visions of Lebanon's identity. Mr Hariri's camp, which includes right-wing Christians, liberals and, increasingly tenuously, the Druze faction led by a suave warlord, Walid Jumblatt, prefer the notion of Lebanon as a neutral, mercantile state. Hizbullah sees the country instead as a bastion of Arab hostility to Israel.

Overwhelmingly backed by Lebanon's Shias, some 40% of the population, Hizbullah has long insisted that its powerful guerrilla force, now believed to have some 50,000 rockets supplied by Iran and Syria, is untouchable. March 14th supporters want it disarmed, and have won aid from the West, especially America, to bolster Lebanon's national army instead. Mr Hariri has avoided provoking his opponents on the arms issue. He has also placated them by trying to mend ties with Syria, severely strained after his father, Rafik, a billionaire and five-times prime minister, was assassinated in 2005. Many Lebanese blamed Syria, which had long meddled in its smaller neighbour's affairs.

Mr Hariri has proved less malleable over the UN-mandated investigation into the murder of his father and 60 others, in a spree of assassinations of March 14th figures between 2005 and 2008. As the investigation has neared the stage of issuing indictments, leaks suggest that Hizbullah people, rather than Syria, may be held responsible. The party and its allies have campaigned furiously to undermine the special tribunal, based near The Hague.

Having persuaded its own supporters that the court is a Western tool and convinced many other Lebanese that the investigation should be buried for the sake of peace, Hizbullah has tried to bully March 14th into rejecting the court's findings. Mr Hariri's refusal to do so led to a prolonged crisis that may now, as his government falls, enter a murkier phase.

Lebanon's politicians, for all their brinkmanship and legacy of violence, have in the past proved surprisingly able to pull off compromises. But this particular circle, pitting Mr Hariri's personal desire for justice against Hizbullah's millennial sense of mission, and indirectly matching American might against Iranian guile, looks hard indeed to square.