ALGIERS// Soldiers in Algeria are reinforcing defences along its mountainous border with Tunisia, across which Tunisian special forces have been hunting a group of militants, the latest threat to Algeria's fragile security. Photographs in the Algerian media showed huge containers filled with sand blocking the border, and hundreds of soldiers to ward off what is perceived here as an outside terrorist threat.
The fighters, according to Tunisian authorities, have links to Al Qaeda and experience of fighting in northern Mali, and are protecting a base with mines.
Algeria, a country clinging to peace after a decade of civil war in the 1990s, faces growing challenges to its security, from inside and outside the country, and has stepped up the operations of its military - the most competent in the region - to contain the threats.
Shocks keep shaking the North African republic: from last year's takeover of northern Mali by Al Qaeda and their associates - many of them Algerian - just along the long southern border, to the cross-border flow of weaponry unleashed by the fall of Libyan autocrat Muammar Qaddafi, and extremists in Tunisia.
Most disastrous was the terrorist attack in January on the In Amenas oil and gas installation in the east of the country. Despite military redeployments, threats still loom and plans to improve security for oil and gas facilities are not convincing enough to tempt some evacuated international oil companies back ti In Amenas and other installations.
The attack, which began on January 16 and resulted in the death of at least 37 hostages, can be attributed to a combination of internal and external problems, according to regional and western security officials.
The mastermind of the attack, Mokhtar Belmokhtar, is a one-eyed militant with 20 years' experience of fighting and, latterly, kidnapping, cigarette smuggling and levying a protection tax on the drug traffickers who criss-cross the desert regions of Mauritania, Mali, Niger and southern Algeria.
The spectacular siege, which transfixed global media, was likely motivated by a desire for Belmokhtar to prove himself against a rival leader, Abdelmalek Droukdel, said Idriss Mounir Lallali, of the African Centre for the Study and Research on Terrorism.
Both Algerians were founders of the Salafist Group for Preaching and Combat, an extremist organisation formed in about 2002. The group forged strong links with Al Qaeda, and eventually morphed into Al Qaeda in the Islamic Maghreb (AQIM), with Droukdel as a leader - based in the mountains in the north of Algeria, near the capital - and Belmokhtar heading a southern battalion.
But in late 2012, after years of deteriorating relations, Belmokhtar, having amassed huge amounts of money from ransoms and smuggling, broke away and formed his own group, the Signed-in-Blood brigade.
In a video posted online dated January 17, 2012, Belmokhtar claimed responsibility for the raid and still claimed allegiance to Al Qaeda.
"We are dealing with people who have ego problems," said Mr Idriss. "He was showing Droukdel 'you have evicted me from the group? That's not a big loss for me, that's a big loss for AQIM'."
"Belmokhtar was trying to render Droukdel irrelevant," he said, adding that contrary to accounts by the Chadian military, intelligence reports indicate that Belmokhtar is still alive and hiding somewhere in the Sahel region which encompasses parts of northern Mali, Mauritania and southern Libya.
In addition to the power struggle within the Algerian part of the organisation, the attack was facilitated by the uprising that overthrew Qaddafi in Libya, which created a security vacuum that left the south of the country ungoverned, said Mr Idriss.
He said that two groups were involved in the plant attack coordinated by Belmokhtar. One was mainly Tunisians, Libyans and Egyptians, trained in Libya and helped across the border by Mohammed Lamine Boucheneb. He was the only other Algerian involved and was killed by Algerian forces on the second day of the siege. Another group came across the border from northern Mali.
"We are facing an international force of mercenaries, backed up and supported by narco-traffickers" said Mr Idriss.
Algerian forces responded to the attack with ferocity, refusing to negotiate and killing a reported 11 kidnappers in air and ground operations. The army was lauded in the national media, but the countries whose employees were killed - Japan, Norway, the UK and others - expressed carefully-phrased doubts about the operation. BP and Statoil, who were the international oil companies operating at the plant, swiftly evacuated and have not returned.
The central debate between Algerian authorities and international oil companies, said a western diplomat in the capital, has long been the presence of foreign security companies and soldiers inside the installations. Algerian authorities, wary of armed foreigners on their soil, forbid private security companies, while oil companies have not allowed Algerian soldiers within the fences of their institutions: although this is now likely to change after the attack.
"[Algerian authorities] have their own way of doing business, and they are hugely resistant to outside ways," the diplomat, who requested anonymity, said. "I don't think they grasped during In Amenas what a big deal it was for some of the countries involved … as far as they were concerned it was an internal issue."
The disagreement over how to secure the oil and gas facilities continues. Reuters news agency reported last week that BP have no plans to return to the country in the immediate future because they are not reassured about security arrangements. Meanwhile, In Amenas and other installations are underproducing oil and gas.
While Algeria is a country with little debt and US$200 billion (Dh734bn) in foreign currency reserves, it relies on oil and gas for the majority of its income and it is imperative that the international oil companies return.
"BP and Statoil are looking for reassurances," said another western diplomat in Algiers. "The Algerian government is very reluctant to accept criticism of how they do security."
However, he said, a number of recently-unveiled security cooperation programmes, including with the UK, France and Germany, amount to a recognition of a need to at least appear to be improving security policy.
"The government recognises that it's more efficient to have BP and Statoil back," he said, "but they're not back yet. So it is a political imperative to be seen to be tackling the problem, and having partnerships."