Who will lead Yemen now?

With President Saleh in Saudi Arabia for medical treatment, Yemen's various opposition groups may have achieved their aim of ousting him, but they have divergent post-Saleh goals.

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Yemen's main political opposition accepted a transfer of power to the country's vice president after President Ali Abdullah Saleh traveled to Saudi Arabia for medical treatment following an attack on his compound Friday. But it's unclear who will replace President Saleh more permanently if he doesn't return, and whether Vice President Abdul Rabu Mansoor Hadi will be accepted by the other groups vying for Saleh's ouster.

Saleh was injured Friday when opposition tribesmen shelled the presidential compound, targeting a mosque during Friday prayers. Saleh's forces and Yemeni tribesmen, who have engaged in pitched battles for nearly two weeks in the capital, continued fighting this weekend, the Washington Post reports, despite a truce brokered by Saudi Arabia.

The capital erupted in fireworks after his departure, which some saw as permanent, given his injuries and increasingly weak political position. But the government rebuffed the political opposition's call for the establishment of a temporary coalition government, saying that Saleh was still Yemen's president and would return to the country soon. In the interim, Vice President Abd al-Rabo Mansur al-Hadi was named as acting president.

US ally Saudi Arabia is expected to block Saleh from returning to Yemen (with US support), the Washington Post reports, but neither the US nor Saudi Arabia likely has an answer for how to ensure a peaceful transition to a new government that will satisfy the secular youth-protest movement's demands for change, command respect from powerful tribes, and be capable of reining in Islamist militants, including an Al Qaeda franchise active in the south.

An editorial from the Daily Star in Lebanon, a country that has long served as a proxy battleground for regional powers, stated, "the complexity of Yemen’s political dynamic almost makes Lebanon seem straightforward." Saleh took much of his family to Saudi Arabia with him, but a son and nephew who command some of the most elite security forces remain in Yemen. Those who were allies in the fight to remove Saleh from power will have competing interests as they build a new government. Fighting could continue as a power struggle emerges.

… A strong secessionist movement exists in the south of the country. In the north, Houthi tribesmen have long clashed with government forces. Al-Qaeda in the Arabian Peninsula also seems to be taking advantage of the turmoil to gain a foothold in the city of Zanzibar.

Meanwhile, the youth of Yemen who worked hardest for Saleh’s ouster will also find themselves colliding with mostly conservative tribesmen. All of these agendas will compete, of course, in the region’s poorest country and one of the world’s most heavily armed.

The Hashid tribal confederation, which led the tribal fighting against Saleh's forces, could be a deciding factor in who comes next and how well he can rule. The tribe is unlikely to seek a "direct political role" in a future government, but its endorsement of the next leader could be critical, and it has the ability to help bring stability to the country, the Wall Street Journal reports.

Even if the disparate opposition elements manage to pull together, the country is still confronted with significant economic and social hardships and the threat of Islamist militants. It is the base for Al Qaeda in the Arabian Peninsula, and an estimated 300 AQAP members are hiding out in the mountains of southern Yemen, the Associated Press reports.

AQAP remains the chief concern of the US as it watches Yemen's government unravel. Under Saleh's rule, Yemen had an alliance with the US based on a joint effort to combat terrorism in the country. At this point, it's unclear whether Saleh's successor would share the same concerns, and in the meantime, the power vacuum could leave an opening for AQAP to expand its reach and carry out attacks, the Washington Post reports.

The Pentagon and the CIA, which have steadily deployed more men and equipment to Yemen, including armed drones, will have to forge fresh relationships with whatever new leadership emerges in Yemen. And some in the opposition to Saleh have expressed skepticism about even the existence of al-Qaeda in the Arabian Peninsula (AQAP), describing the terrorist group that has come to preoccupy Washington in recent years as a myth. …

In recent weeks, US officials said, Yemen’s counterterrorism forces, including special forces units that the US has helped fund and train, have been sent back to their barracks or diverted from the pursuit of AQAP militants.

If the unrest continues, the US may consider acting more unilaterally in Yemen, increasing its use of armed drones against militant strongholds.

But another opening remains for the US: helping a new government avert a looming economic collapse, according to Christopher Boucek, an analyst with the Carnegie Endowment for International Peace. “My guess is that there is no money left in the bank, that the economic collapse is even worse than we think. The US can help with economic development, resource depletion, all the things that cause instability. And it can say you also need to help us do something about AQAP," the Post quoted him as saying.