Analysis by CNN's Paul Cruickshank and Tim Lister
If Younis al-Mauretani has been arrested in Pakistan, it is another significant blow against the operational ambitions of al Qaeda. Counter-terrorism analysts say he had become a key planner for the group in recent years - and he appears to have had direct contact with Osama bin Laden.
Like many in al Qaeda, al-Mauritania adopted his country of origin as his last name. He was from the sparsely populated desert state of Mauritania in north-west Africa. Al Qaeda has recruited extensively from Mauritania and neighboring countries, where al Qaeda in the Islamic Maghreb now has a foothold.
Al-Mauretani's stature within al Qaeda appears to have grown in the last two years. According to European intelligence officials, he was involved in planning attacks in Europe in the fall of 2010. Fears that such attacks would materialize led the U.S. State Department to issue a travel alert in October 2010. The alert said that "current information suggests that al Qaeda and affiliated organizations continue to plan terrorist attacks." It added that some European governments were warning of "heightened threat conditions."
German intelligence especially was anxious about the possibility of attacks on soft targets, such as shopping centers and hotels. "The threat is being taken very seriously - an attempt at an attack is considered likely," one German official told CNN in October last year.
Al-Mauretani is thought to have taken charge of a group of German jihadists from Hamburg who had arrived in Pakistan's frontier territories in March 2010, according to German intelligence officials. To al Qaeda, such individuals were highly valuable: they had legitimate travel documents and homes in Europe. They could be trained and then sent back to carry out terrorist attacks. The same applied to Najibullah Zazi, a U.S. resident of Afghan descent. who received bomb-making training in Waziristan before returning to the United States. He confessed to planning a suicide bombing on the New York subway.
But one of that German group, Ahmed Sidiqi, was detained while visiting Kabul in July 2010 and handed over to U.S. forces. According to European counter-terrorism sources, Sidiqi began to divulge details of the plot in Europe while being questioned at Bagram airbase. The sources said Sidiqi had claimed that four other members of the group were involved in an al Qaeda conspiracy to attack European countries. European officials said Sidiqi soon told interrogators that while in the tribal areas of Pakistan he met with al-Mauretani.
Another of the German group, Rami Makanesi, was arrested in Pakistan last year and sent back to Germany, where he faces trial. According to the German magazine der Spiegel, Makanesi told interrogators more about the groups' meetings with al-Mauretani in the spring of 2010.
He said a man arrived in a Toyota SUV who called himself Mohammed Younis al-Mauretani. He was slim and had dark eyes, a sharp chin and curly brown hair and knew the entire Koran by heart, according to Makenesi's account.
Makanesi told al-Mauretani that he could raise money for al Qaida in Germany. "Perfect. That's exactly what I would like," al-Mauretani allegedly replied.
According to Der Spiegel, al-Mauretani told the Germans that he had reached out to Osama bin Laden through Atiyah abd al Rahman, al Qaeda's commander in Waziristan, requesting that al Qaeda establish a cell in Germany.
Unconfirmed reports say that documents uncovered from the Abbottabad compound where Osama bin Laden was killed included evidence of direct contacts between the al Qaeda leader and al-Mauretani about the European conspiracy. Notably, the Pakistani announcement Monday of al-Mauretani's arrest said that he was "tasked personally by Osama Bin Ladan to focus on hitting targets of economical importance in United States of America, Europe and Australia."
It is possible that information from Sidiqi - and/or documents found in the bin Laden compound - provided clues in the hunt for al-Mauretani. Der Spiegel reported earlier this year that Sidiqi's information helped German intelligence break up another plot led by a 29-year old Moroccan national, Abdeladim el-Kebir. El-Kebir was arrested in April with two other men and accused of planning a bomb attack against civilians in Germany.
El-Kebir had also left Germany in early 2010 and trained in an al Qaeda camp, according to German sources. They said el-Kebir had been instructed to carry out a bombing by a senior al Qaeda member. Unconfirmed reports say letters from al-Mauretani were found in el-Kebir's apartment in Dusseldorf, but German counter-terrorism sources quoted by Der Spiegel say el-Kebir had also met Atiyah abd al Rahman.
If al-Mauretani has indeed been captured, it is another significant blow to al Qaeda's ability to export terrorism from Pakistan's tribal territories. Besides the death of Osama bin Laden, other senior figures in the organization who have been killed in recent months include Ilyas Kashmiri, who also had plans for attacks in Europe and had a long history of successful terror attacks in India. Kashmiri had boasted that Europe would suffer similar attacks to the one in Mumbai that killed nearly 200 people.
And last month, Atiyah abd al Rahman - the link between Osama bin Laden and Mauretani - was reported killed in a drone strike. Rahman was one of the handlers of Bryant Neal Vinas, a U.S. citizen who plotted to bomb the Long Island Rail Road in 2008, and had become one of al Qaeda's senior strategists.
In the space of four months, al Qaeda has lost not just its leader, but three of its most effective commanders.