The implications of such a buildup in Yemen are profound not only for the stability of Saudi Arabia — the birthplace of Islam and home to the holiest of Islamic shrines — but for the world's dependence upon a continued flow of petroleum from the largest known oil reserves.
(Left: Saeed Sankar and others inside a court cage react as a state security court in San'a, Yemen handed down death sentences to six al Qaeda militants convicted for a number of deadly attacks on Western targets last year, on Monday, July 13, 2009.)
For years, Western intelligence officials have believed that Osama bin Laden would eventually aim to destabilize Saudi Arabia, his own birth place. Bin Laden traveled to Afghanistan in the 1980s to join the U.S.-led and Saudi-supported "jihad" (or holy war) against the Soviet occupation. While Soviet troops withdrew in 1989, large numbers of Arab volunteer fighters remained in Afghanistan.
"The trend is very, very clear," one Western diplomat based in Islamabad told CBS News on condition of anonymity. "There is no question about Arab members of al Qaeda increasingly seeking ways to travel to Yemen.
"Some have been arrested along this route," said the official, who refused to name the countries in which arrests have taken place, or the number of people arrested.
A senior Pakistani official who spoke to CBS News confirmed that Arab militants linked to al Qaeda were heading to Yemen in growing numbers. The Pakistani official claimed the militants had traveled to Yemen via Iran, using remote locations along the southern Iranian coast to discretely board fishing vessels.
However, the Western diplomat said it was not possible to establish a single route taken by the militants. "It is impossible to say if these people made their transit in Iran or just traveled out of Pakistan to another country first before reaching Yemen, or may have found ways to sail straight to Yemen" he said.
"Yemen is the final destination. These days, there are many in the intelligence community who believe Yemen has become the new big magnet for these people," said the diplomat.
The revelation of militants transiting to Yemen, with the likely intention of trying to destabilize Saudi Arabia, follows .
The prince survived the attack, but Western officials familiar with al Qaeda's activities in the Arab world warned that the incident only underlined the growing determination of militants to undermine the country, in an apparent attempt to disrupt global oil distribution.
By CBS News' Farhan Bokhari reporting from Islamabad
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Country Fast Facts: Yemen