By Maria Golovnina and Mohammed Abbas
LONDON, Jan 23 (Reuters) - Britain has vowed a tough response against militants in North Africa, but behind its tough language lies the ugly reality of a fast-shrinking army, deep budget cuts and little U.S. interest in another costly war in a distant desert.
Enraged by the death of British citizens in a hostage taking crisis in Algeria, Prime Minister David Cameron has called for a global response to jihadist threats in North Africa and warned it could take decades to tame the increasingly volatile region.
Unlike France, whose move to send troops to nearby Mali this month is an echo of its own colonial past in Francophone Africa, Britain faces the uphill task of finding a relevant role to play in what could be a new phase in the global war against terror.
Further dampening Cameron's hopes for coordinated action, his own government announced sweeping cuts to the army this week as recession-hit Britain struggles to plug a yawning budget gap.
"We've frankly run out of treasure to be doing this," a former senior military official told Reuters.
"The Americans are key," he said, adding that Britain realises that unless it goes in with an enormous force it will not be decisively influential.
Unrest in North Africa has long been a headache for Western powers, but the region shot back to the top of global agenda after a bloody hostage siege in Algeria and France's intervention against Islamist fighters in neighbouring Mali.
No sooner had French bombers started pounding rebels in northern Mali on Jan. 11, than al Qaeda-linked militants struck back by storming a desert gas plant in Algeria in a hostage taking crisis in which dozens of people were killed.
Britain and its Western allies are concerned about the emergence of the so-called arc of instability spanning from Taliban bases in Pakistan all the way to Africa, which has allowed jihadists to regroup and entrench in places like Mali.
The growth of al-Qaeda's North African wing, known as Al Qaeda in the Islamic Maghreb, is at the heart of these concerns, as well as the rise of local copycat groups driven by a mixture of religious zeal, cross-border crime and separatism.
All three - France, the United States and Britain - are permanent U.N. Security Council members but their vision of how to tackle North Africa, with its treacherous terrain, porous borders and erratic tribal alliances, does not always overlap.
Seeking to jolt his Western allies into action, Cameron described North Africa as a "magnet for jihadists" this week, vowing to boost intelligence aid to Algeria and consider giving more help to France to fight Islamists in Mali.
Britain is providing France with two C-17 military transport aircraft for Mali and has pledged to send dozens of soldiers to a European Union mission to train Malian government forces.
Cameron's office has ruled out any direct military intervention but on Tuesday, the Times newspaper reported that British forces had been put on alert for a "fully-fledged battle against al Qaeda" in northern Africa.
Few experts take this possibility seriously, given Britain's dwindling military clout and budget constraints.
"I think what's being talked up now in terms of an existential threat is warming up the British public," said the military official, who was not authorised to speak publicly.
"But to be honest until someone with a Algerian, or Malian or Nigerian pedigree comes and puts a bomb in London on a bus, on the tube (metro), no one's going to take any notice. The popular opinion will be: 'It's not our problem'."
Bringing his rhetoric back to earth, Cameron's own defence ministry announced 5,300 job cuts in the army on Tuesday, the same day the prime minister chaired a national security council meeting to discuss developments in Africa.
ANOTHER LONG CONFLICT?
France, by contrast, was quick to send troops and fighter jets to Mali to stop the advance of Islamist rebels who had seized an area the size of Spain in the north and declared Sharia law, banned all music but the Islamic call to prayer.
France's motives are however entirely different.
Still haunted by the ghosts of its own colonial experience in Africa, France has a long history of interventionism on the continent, having launched dozens of operations there since the 1960s in a policy known as Françafrique.
But the U.S. response has been markedly muted. Already accelerating plans to pull out troops from Afghanistan, it has shown no desire to get dragged into another conflict that could overshadow President Barack Obama's second term in office.
Like other Western players, Washington is unnerved by the rise of militancy in the Sahara region but its involvement there has been confined to quiet intelligence gathering and sharing, predominantly alongside the Algerian government.
"The Americans since 9/11 have built up quite a strong presence in the Sahel, which they don't really communicate about very much," said Francois Heisbourg, a special adviser at the Foundation for Strategic Research, a Paris-based think-tank.
"I am not sure how strong the Brits are in terms of their own technical intelligence means in the region."
Washington is also anxious to avoid any repeat of its painful experience in Afghanistan where U.S. support for anti-Soviet mujahedeen eventually gave birth to al Qaeda itself.
In Mali, coup leader Captain Amadou Sanogo, who last year helped topple a Mali president seen in the West as a linchpin in its fight against al Qaeda in Africa - had been himself previously trained by the U.S. military. (Additional reporting by Guy Faulconbridge in London, Adrian Croft in Brussels; Writing by Maria Golovnina; Editing by Giles Elgood)