Yemen has often been portrayed as a country on the brink of catastrophe. Equally often, it has defied expectations and muddled through – if only just. But the suicide attacks on two mosques that left at least 142 people dead in Sana’a last Friday are one sign, among many, that it has finally tipped over the edge.

The UN is warning helplessly about a rapid downward spiral and calling for a resumption of efforts towards a political settlement, but the prospects of that happening are virtually nil and the scene is set for a protracted civil war with multiple protagonists.

Inside Yemen, the lineup of forces is complicated. One key player is Ali Abdullah Saleh, who was ousted from the presidency in 2012 after 34 years in power and has been causing trouble ever since.

Saleh appears to be colluding with the Houthis, whom he previously fought in a series of wars in the far north of the country. His alliance with the Houthis is seen by many as a tactical move aimed at eventually installing his son, Ahmad, as president.

Yemen mosque bombings 'could only be done by the enemies of life' – president
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The Houthis – officially known as Ansar Allah (the Supporters of God) – belong to the Zaidi sect, a branch of Shia Islam, and had long been marginalised. Last September, however, their fighters swept unexpectedly into the capital and, meeting negligible resistance, seized control of it.

Although the Houthis managed to bring down the government, they have so far failed to assert control over the whole country and, left to their own devices, are probably incapable of doing so. But that doesn’t stop them from trying, and on Saturday they entered the central city of Taiz, which is seen as a stepping stone towards an attempted takeover of the south.

Ranged against Saleh and the Houthis is Abd-Rabbu Mansour Hadi, who succeeded Saleh to the presidency. After arriving in Sana’a, the Houthis put Hadi under house arrest and pressed him into resigning.

Hadi escaped, withdrew his resignation and resurfaced with some of his entourage in the southern city of Aden, which he is trying to establish as an alternative capital.

Both Hadi and Saleh have support from different sections of the military, and clashes have broken out between them. Last week, Hadi’s Aden compound was hit by an air raid, and gunfights closed Aden airport for several hours.

Also in the south, fighting near al-Anad airbase on Friday triggered the hasty evacuation of the last remaining US special forces in the country. Later, pro-Hadi forces, including tribal militias, captured the base from pro-Saleh forces.

It remains to be seen, though, whether Hadi is truly welcome in the south, where the Herak movement has been agitating for independence from the north. Hadi is himself a southerner but, having spent 17 years as Saleh’s deputy, he may be too closely associated with what the separatists regard as northern domination.

Hadi is still recognised by the UN as Yemen’s president but his legitimacy is wearing thin. His accession to the presidency was ratified, after a fashion, in a one-candidate “election” and his term in office was originally supposed to last only until 2014.

The Guadian

In the north, meanwhile, and following their conquest of Sana’a, the Houthis have been settling old scores with the Sunni-Islamist Islah party – previously the largest of Yemen’s opposition parties. For religious reasons, the Houthis are also, of course, sworn enemies of al-Qaida, whose presence in Yemen seems undiminished despite numerous drone attacks by the Americans.

The two mosques attacked by suicide bombers on Friday were linked to the Houthis. Responsibility has been claimed in the name of Islamic State, though the authenticity of that claim has been disputed. AQAP, the local branch of al-Qaida, denies any involvement – in line with its recently declared policy of refraining from attacks on civilians.

Isis has not previously been active in Yemen and if its claim turns out to be true, this will add an alarming new dimension to the developing conflict.

But regardless of who was behind the Friday bombings, slaughtering fellow Muslims as they pray intensifies sectarian aspects of the conflict that have not been particularly apparent until now, and invites reprisals of a similarly bloody kind.

So far, this is primarily an internal conflict but the longer it continues the more likely it is to become internationalised – especially in the context of Sunni-Shia rivalries in the region. Neighbouring Saudi Arabia has always meddled in Yemeni politics, and its most recent military intervention, in 2010, took the form of air strikes against the Houthis. The more Saudi Arabia becomes involved, the more likely it is that Iran will step up support for the Houthis.

It need not have come to this. In 1993, shortly after the unification of north and south, Yemen became the first country in the Arabian peninsula to hold multiparty elections under universal suffrage. But despite high hopes at the time, electoral politics didn’t deliver – mainly because Saleh was unwilling to accept the possibility of being voted out of office. In 1999, when Yemen held its first contested presidential election, Saleh’s only opponent was an obscure member of his own party whose campaign expenses were being funded by Saleh. Saleh was duly elected, with 96% of the votes.

Hopes flickered again in 2011 when tens of thousands of Yemenis, across a broad political spectrum, took to the streets calling on Saleh to resign. Central to these protests was the emergence of a new generation of political activists who set up camp near Sana’a university in an area they named Change Square – and stayed there for months.

Saleh resisted, clinging to power in the face of this popular uprising for more than a year. He eventually stepped down under a deal brokered by the Gulf Cooperation Council (GCC) and approved by the UN.

Ludicrous as it might seem to entrust the GCC’s autocratic monarchies with shaping Yemen’s post-Saleh development, that is what happened. The GCC deal sidelined the youth activists and stymied the revolution. It provided for Saleh to hand power to his deputy, Hadi, but much of the old regime remained intact.

Worst of all, Saleh was granted immunity from prosecution and allowed to stay in Yemen. That, more than any other single decision, contributed most to deepening the political crisis.