Yemen heads toward civil war as Saleh escalates fight with major tribal leader

• A daily summary of global reports on security issues. This article was updated at 8:53 a.m.

Yemen President Ali Abdullah Saleh ordered the arrest Thursday of Sheikh Sadiq al-Ahmar, the leader of Yemen's most powerful tribal confederation. The move could escalate already serious clashes in Sanaa between security forces loyal to Saleh and thousands of armed tribal fighters, potentially igniting civil war.

Fighters loyal to President Saleh and Mr. Ahmar clashed overnight Wednesday in the capital Sanaa, leaving dozens dead, according to Al Jazeera. The fighting has raged since Monday, after yet another deal for Saleh to step down failed. An ammunition store belonging to Mr. Ahmar's fighters exploded Wednesday night, killing 28, Agence France-Presse reports.

Ahmar is the titular head of the powerful Hashid tribal confederation, which also includes Saleh's family. His younger brother Hussein bin Abdullah al-Ahmar was a former member of Saleh's government, but resigned from the ruling party in March and threw his weight behind the protesters, joining their calls for Saleh to step down. Saleh has reportedly called for the arrest of all 10 Ahmar brothers, whose fighters have captured about 70 members of Yemen's security forces and declared they won't stop fighting until Saleh resigns. (Editor's note: The original version misstated which Ahmar brother resigned from the ruling party.)

According to the The Wall Street Journal, about 10,000 members of the Hashid tribal confederation have come to Sanaa in recent days to join the fighting. They have gained control of several government building in the fighting, including the Ministry of the Interior. There are about 30,000 troops from Yemen's Republican Guard and security forces deployed throughout Sanaa, led by Saleh family members. Pitched battles between Saleh's security forces and armed tribesmen is a "worst-case scenario" for the US, the Journal notes.

Amid the rapidly deteriorating security situation, on Wednesday the US ordered all nonessential diplomats out of the country and urged any Americans living there to leave, the Associated Press reports – a big step up from the previous travel warning, which allowed nonessential diplomats to leave but did not order it and merely suggested that Americans consider leaving.

Saleh told reporters Wednesday that he would not allow the country to be dragged into a civil war, nor would Yemen become a "failed state" under his leadership, Al Jazeera reports. "What happened was a provocative act to drag us into civil war, but it is limited to the Ahmar sons," he said, referring to the recent clashes in the capital.

He also said that he would sign the deal brokered by the Gulf Cooperation Council (GCC) that calls for him to step down within 30 days. He has made that claim before, only to back out at the last minute three times in a row – most recently this past weekend.

The US is watching Yemen anxiously, concerned that the instability and fighting between Yemeni factions is allowing the local Al Qaeda franchise, Al Qaeda in the Arabian Peninsula, a window of opportunity to expand its operations while eyes are watching Sanaa.

Yemen expert Gregory Johnsen, a former Fulbright in the country who is now a PhD student at Princeton University specializing in Yemen, says that the US is almost out of options and that the current predicament is a result of years of misguided policies.

Ignoring the country for a decade, and then spending the next decade tying US aid so closely to al-Qaeda's presence in the country, and then funneling all that money and equipment through a single family all is going to hurt the US. Although, of course, all of the above is a result of only seeing Yemen as a [counterterrorism]-problem that had to be solved.

... These mistakes can't simply be wished away, there are consequences, sometimes severe ones, for mistakes in policy - and the US doesn't get unlimited chances to do it right. Over the past three months the US got a single chance - the one thing it could control in a world of uncertainty - and it decided to put its money on the GCC and its deeply flawed plan.

By taking a back seat to the GCC plan, the US squandered away its leverage and influence when it still could have made a difference to Salih's thinking. Now, he isn't going to sign the plan and he's involved in a major fight with the al-Ahmar family.... My suspicion is that Salih's planning is to defeat the al-Ahmar family decisively...