Yemen has been a battleground between the West and al-Qaida for years. It's also torn by what amounts to a three-way civil war.

Now it's emerging as an arena in the religious-driven confrontation between Iran and Saudi Arabia.

After years of internal conflict and the enforced 2012 departure of longtime President Ali Abdullah Saleh in a political deal with the Americans and the Saudis, there was hope that one of the Arab world's poorest nations was seeing a glimmer of light at the end of the tunnel.

But once again Yemen, strategically located at the southwestern tip of the oil-rich Arabian Peninsula and dominating key shipping routes, is caught up in the deepening power struggle between Shiite Iran and the Sunni monarchies of the Persian Gulf.

These powers are exploiting deep tribal divisions and fault lines within the armed forces for their own ends and pushing the country into further torment and turmoil.

All this is taking place as Yemen struggles to find its way to some sort of normality after years of conflict and the fall of Saleh after he narrowly survived an assassination attempt.

He was forced out after a bloody pro-democracy uprising under a deal brokered by the United States and Saudi Arabia that allowed him to leave the country.

Saleh was replaced by his longtime deputy, Abd-Rabbu Mansour Hadi, who was backed by pledges of billions of dollars in foreign aid and required to have elections by February 2014.

He faces a host of problems: deep-seated rivalries within the military, where Saleh had placed family members in key commands, al-Qaida's depredations, pervasive tribal rivalries, a secessionist movement in the south and a simmering rebellion in the north.

"Yemen's now open to all," said Ali Saif Hassan, director of the Political development Forum, a think tank in Sanaa.

"From America, from Europe, from Saudi Arabia, from Iran -- and from Qatar."

That tiny gas-rich emirate, a longtime rival of its vast neighbor Saudi Arabia, has aspirations of becoming a regional power and has been conducting a quirky foreign policy critics say has heightened the turbulence that's been sweeping the Arab world in recent years.

Qatar's pressing to boost its influence in Yemen, as much to undercut Saudi Arabia, which has long considered Yemen, its southern neighbor, to be within its purview.

The emirate has established strong links with Yemen's al-Islah Islamist movement, which makes it a player with the potential to block Saudi efforts to pacify the country.

In the north, separatist Shiite tribesmen known as Houthis are rising again, as they have periodically since 2005.

Sanaa says they're funded and armed by Shiite Iran to thwart Saudi plans to pacify Yemen and to eliminate the threat from al-Qaida, which has vowed to destroy the House of Saud.

"In addition to airstrikes and military campaigns, the government has sought to prevent al-Qaida from expanding its operations by employing local tribes to fight the militants, a tactic also used during Saleh's regime," the U.S. global security consultancy Stratfor observed.

"How long the government can rely on these tribes to do its bidding remains unclear, however, due to the fluid nature of their loyalties, which are guided by financial incentives from Saudi benefactors or from rival factions within Yemen."

Overcoming the fault lines running through the armed forces, some based on tribal loyalties, is critical if Hadi's to unify the military and consolidate power while undermining his rivals.

If he can't pull the army, then the country, together, Yemen may well split along traditional north-south lines, with al-Qaida established in the south.

The country was once divided between an ancient monarchy in the tribal-oriented north and a socialist-leaning republic in the south. In 1963, civil war broke out in the north after the hereditary ruler was overthrown. The royalists were supported by monarchist Saudi Arabia, the rebels by Egypt under Gamal Abdel Nasser.

Nasser was forced to withdraw after his defeat by Israel in 1967.

Saleh, an army officer, seized power after a succession of coups. In May 1990 he united north and south but that never took and the south tried to secede in 1994, triggering a four-month civil war. Saleh won through sheer firepower.