The grim prospect of civil war in Yemen has drawn closer as mutinous soldiers have become more deeply involved in a rapidly spreading battle against regime forces for control of the capital.
A negotiated cease-fire Tuesday halted three days of fighting that killed dozens of people, but it will not hold without a quick resolution of the key dispute: Who will lead the nation.
A peaceful way out of Yemen's seven-month crisis may not come easily, if at all, making it more likely to be settled in large-scale and ruinous street battles pitting renegade army soldiers and their allied tribal fighters against U.S.-trained forces loyal to embattled President Ali Abdullah Saleh and led by his son and one-time heir apparent, Ahmed.
Already, pro-regime forces reinforced their positions in their strongholds in the south of the capital, apparently in anticipation of renewed fighting. The potential for bloody strife has been shown in Yemen since the uprising against Saleh's regime began in February, with hundreds of protesters killed and thousands wounded at the hands of security forces.
In the past three days, pro-regime forces killed more than 70 people, mostly protesters, using anti-aircraft guns, rocket-propelled grenades and mortars. At least 23 people were killed in Sanaa on Tuesday as the fighting intensified and spread to sensitive areas of the capital before the cease-fire took hold after nightfall.
In one incident, 13 followers of a tribal leader who changed sides and joined the opposition in March were killed when mortar shells fired by pro-government forces rained down on the upscale Hedah area of southern Sanaa, also home to top regime figures.
"It's a war zone," said Sanaa activist Hakim al-Masmari. "We can't even sit near windows because we could be killed."
Thousands have been forced to flee Sanaa for the relative safety of rural areas. Scores of pickup trucks and cars loaded with families and their belongings were seen early Tuesday heading out of the city, repeatedly shaken by loud explosions overnight.
The United States condemned the violence and called on all parties to exercise restraint. "We urge a prompt, impartial investigation into the events that led to the recent violence," Victoria Nuland, the State Department's spokeswoman, said in a statement Tuesday.
Saleh, Yemen's president for 33 years and a staunch U.S. ally, has clung to power despite tens of thousands taking to the streets nearly daily since February to demand his ouster. At least three times he has backed away at the last minute from endorsing a resignation plan offered by his Gulf Arab neighbors and supported by the United States _ handing over power in return for immunity.
He left Yemen in June for neighboring Saudi Arabia to be treated for serious wounds suffered in an attack on his compound. He has not returned to Yemen since, but the presence in Sanaa of his son, Ahmed, and other loyal family members meant the regime continued to fight for its survival.
Much is at stake in Yemen for the United States, its Gulf Arab allies, particularly Saudi Arabia, and the West. Yemen overlooks key shipping lanes in the Red and Arabian seas and is home to one of the world's most dangerous al-Qaida branches, whose militants have staged or inspired a series of attacks on U.S. territory. Already, the chaos has allowed al-Qaida militants to capture and hold a string of towns in nearly lawless southern Yemen.
With the prospect of a peaceful settlement remote, civil war becomes a realistic possibility, given that Yemen is a nation with deep tribal and regional divides, a checkered history of civil strife, and a chronically weak central government.
The nation's north and the once-independent south fought it out in 1994. Another civil war would pit the renegade soldiers of the 1st Armored Division, perhaps the nation's most combat-tested unit, against the Republican Guards led by Ahmed to decide the leadership question.
The 1st Armored Division claims about 20,000 fighters in Sanaa, and, according to security officials, has been training its men in urban warfare for most of the six months since it defected along with its commander, Maj. Gen. Ali Mohsen al-Ahmar, and joined the anti-Saleh protesters. The division has tanks and armored personnel carriers but they have been hidden across the city to avoid being picked off by regime warplanes.
The Republican Guards boast much more armor, a large arsenal of rockets and about the same number of troops. As a backup, it can draw on the support of the U.S.-trained and equipped Special Forces, another elite unit also led by Saleh's son, and the Presidential Guards, led by Saleh's nephew, Tariq, a commander notorious for brutality.
"The Republican Guards are the superior force on paper," said military expert Hussein Mansour, a retired army brigadier. "But that makes little difference on the ground. It is all about street warfare and combat expertise."
The division, which took part in every war fought in Yemen in the past three decades, also has al-Ahmar for a seasoned commander whose combat experience is complemented by years as Saleh's point man on the country's complex tribal politics.
Ahmed, by contrast, has little combat experience and support outside segments of the military and several small tribes still loyal to him and his father.
The 1st Armored Division has endeared itself to the thousands of protesters camped in Sanaa's central Change Square since its mutiny in March, pledging to protect them from by pro-regime forces.
The protesters have given the division weapons seized this week from a Republican Guards' camp in the city and government buildings as part of a stepped-up campaign against the regime. Unarmed, they also acted as human shields for the soldiers, providing them with cover until new positions in the capital were built and fortified.
Hendawi reported from Cairo.