- Saudis better equipped but lack guerrilla war experience
- Evacuation of civilians points to extended conflict
- Al Qaeda seen as main beneficiary of border war
By Ulf Laessing
RIYADH, Dec 22 (Reuters) - Saudi Arabia faces a long mountain war with Yemeni rebels that might complicate efforts to prevent infiltration by al Qaeda militants based in its unstable southern neighbour, diplomats and analysts say.
Last month, the Saudis launched a military offensive against the Shi'ite rebels, known as Houthis after their leader's clan name, after a rebel cross-border incursion.
The Gulf Arab state, OPEC's biggest oil exporter, has sophisticated Western arms such as F-15 fighters but has little experience in fighting a guerrilla war in the mountains bordering Yemen, military experts say.
"The Houthis are using unconventional warfare against a state power possibly unequipped and untrained for this type of fight," said Theodore Karasik, director of research at the Institute for Near East and Gulf Military Analysis in Dubai.
Saudi Arabia and its U.S. ally worry that al Qaeda is trying to use Yemen, where the Houthis are fighting government forces, as a launch pad for attacks in the kingdom and beyond.
With just two major roads linking the two countries, experts say the 1,500-km (940-mile) border covering mountains, hills, caves, valleys and a remote desert is almost impossible to seal.
Saudi Arabia plans to build a high-tech fence but, with its forces now engaged in border fighting, this might be difficult to start in the near future and al Qaeda might step up infiltration across other parts of the border, analysts say.
There is no evidence supporting Yemeni allegations that al Qaeda has links to the Houthis, but some diplomats and analysts say the Sunni militant group might try to use the rebels or at least exploit the chaos in the border area.
"It is almost certain that al Qaeda are using the fighting as an opportunistic event," said Ghanem Nuseibeh, senior analyst at risk consultants Political Capital in Dubai.
Little is known about the conflict in a region kept largely off limits to outsiders by the Saudi and Yemeni governments, with rebels and the kingdom blaming each other for the fighting.
Analysts and diplomats say the Houthis may have attacked Saudi Arabia to keep the kingdom busy at the border and prevent it from helping Yemen. Riyadh denies giving any military help but cooperates with Sanaa in fields such as intelligence, diplomats say.
Saudi forces have exchanged fire with rebels almost daily since the fighting began, journalists in the border region said. Shelling is sometimes audible 35 km (20 miles) from the border.
MOUNTAIN WARFARE
Karasik said Saudi Arabia had special forces which could operate in mountains but its army was trained for warfare against regular troops and last saw major action in 1991 as part of a U.N.-led coalition that drove Iraqi forces out of Kuwait.
Saudi soldiers in the southwestern region of Jizan said rebels used snipers or approached disguised in women's clothes.
"Their snipers are very young, but good. They aim at your head," a Saudi officer told Reuters.
In the past few days, Saudi television has reported heavy shelling and gunfire by armoured vehicles attacking the positions of rebels, described as "infiltrators" by Riyadh.
"The Saudis fire off a lot of heavy material, but this is a difficult battle with rebels hiding in caves or valleys like in Afghanistan," said a diplomat in Riyadh.
"The biggest achievement for the Saudis is that they managed to contain the fighting to some areas. That's the best they can hope for for now -- preventing it from spreading," he said.
Stability in Saudi Arabia is of global concern because the kingdom controls more than one fifth of crude oil reserves, is a major holder of dollar assets and a linchpin of U.S. regional policy.
Yemen said last week its security forces had foiled a planned series of suicide attacks by al Qaeda.
The incident confirmed Saudi worries about Yemen becoming a haven for al Qaeda to regroup from the losses it suffered in the kingdom during a deadly three-year armed campaign that was halted, with the help of foreign experts, in 2006.
Diplomats say Riyadh wants a buffer zone along parts of the southern border, where the war with Houthis has forced the evacuation of at least 20,000 Saudis from more than 240 villages.
King Abdullah has said the government will build 10,000 housing units to accommodate displaced Saudis.
"This points not only to a lengthy confrontation but also a large number of either existing or expected refugees," said another diplomat in Riyadh.
One challenge for the authorities is that residents in many of the villages in the Jizan region have family ties on the other side of a Yemeni border notorious for the smuggling of arms, alcohol, migrants, and sometimes al Qaeda militants.
"The war is very convenient for smugglers and al Qaeda. They keep the Saudis busy at a border that is already in difficult to control in peace time," said a diplomat in Riyadh. (Editing by Andrew Dobbie)