* Failure of Yemen crackdown would increase regional risk
* Al Qaeda cooperation with Somali militants a worry
* Weak government likely to struggle even with U.S. help
By Cynthia Johnston
DUBAI, Jan 26 Al Qaeda militants could strengthen their foothold in Yemen and form part of a belt of Islamist instability linking Asia to Africa if the government in Sanaa fails to crack down decisively against them, analysts say.
An impoverished country that is strategically located on one of the world's busiest shipping lanes, Yemen has declared war on al Qaeda under pressure from Washington and Saudi Arabia, its oil-producing neighbour.
Over the past weeks, it has claimed to have killed six al Qaeda leaders in an air strike in the north, captured three militants close to the Saudi border and shot dead another member in an exchange of gunfire in Lahj province in the south.
But even if these early successes prove true -- al Qaeda disputes local leaders were killed in the strike -- Yemen faces a daunting challenge containing militants who will hunker down and seek to exploit their ties to like-minded groups in Somalia, Afghanistan and Pakistan to sow regional chaos.
"Al Qaeda in Yemen is a regional command. It is not a national command. It is a command for the whole Arabian peninsula. So theoretically at least we are talking about seven states," Dubai-based security analyst Mustafa Alani said.
The most direct threat from a stronger al Qaeda foothold in Yemen is to Saudi Arabia, which shares a 1,500 km porous land border with its southern neighbour.
Saudi Arabia halted an al Qaeda campaign in the kingdom in 2006 after a wave of attacks on foreign residential compounds, government targets and energy installations.
But last year, the Yemeni and Saudi wings of the group merged to form the Yemen-based Al Qaeda in the Arabian Peninsula (AQAP). Its Christmas Day attempt to blow up a U.S.-bound airliner made it clear that the merged branch has its sights on targets far beyond mountainous Yemen's borders.
Hassan Abou Taleb, an analyst at the Cairo-based al Ahram Centre, said one issue of concern is a strengthening of ties between Yemen-based al Qaeda and militants in Somalia, a failed state that is home to pirates who prey on international shipping.
Worried about such an alliance, Yemen has already ramped up coastal security to block entry of Somali fighters disguised as Horn of Africa refugees.
Somalia's al Shabaab movement, seen by Washington as al Qaeda's proxy, and with known links to Yemen militants, has said it was ready to send backup to Yemen should the U.S. carry out strikes there.
"If both al Qaeda in Yemen and the religious youth in Somalia united ... can you imagine what would happen in the future? I think a lot of damage, a lot of instability," Abou Taleb said. "Also this will encourage al Qaeda to spread more and more, not only in the Arabian Peninsula but also in Africa."
Al Qaeda is no newcomer to the Gulf region. Yemen is the ancestral homeland of Osama bin Laden and has long been a support base for his followers, who have sought to forge links with tribes in areas where government control is already weak.
Militants bombed the Navy warship USS Cole in Aden harbour in 2000, killing 17 U.S. sailors. Two years later an al Qaeda attack damaged a French supertanker in the Gulf of Aden.
Other Gulf states are also rich in targets for the militant group, which has long condemned Arab regimes it believes have brought decadence and Western influence to the Muslim heartland.
Kuwaiti authorities said in August they had foiled an al Qaeda-linked plan to bomb a U.S. Army camp and an oil refinery.
STOKING BEES NEST
Yemen, an Arab state verging on collapse, has been tasked with stopping al Qaeda at home in order to prevent it from expanding its reach.
The Obama administration is considering proposals to sharply expand Pentagon powers to assist forces in Yemen. But even with U.S. backing, analysts are sceptical about the government's ability to clamp down on al Qaeda.
Yemen has one of the weakest central governments in the Arab world and is already overstretched in its fight against a separate northern Shi'ite revolt and southern separatists.
It also faces a water shortage and is battling to turn around declining oil output from mature oilfields. An international conference in London this week will examine ways to boost aid while ensuring the government is held accountable for economic reform.
Air strikes of the kind Yemen used in attacks on the house of local al Qaeda leader Ayed al-Shabwani in recent weeks are unlikely to prove an effective weapon in the longer-term and could even end up stoking resistance.
Theodore Karasik of the Institute for Near East and Gulf Military Analysis likened the strikes to "aggravating a bees nest".
"If they (al Qaeda) are really squeezed they can just pick up and run to someplace else," he said. "But the way the situation is going now it only seems to me it might actually get worse before it gets better."
(Editing by Noah Barkin)