The U.S. military is expanding its key counter-terrorism base in Africa, Camp Lemonnier in Djibouti, as Washington escalates a secretive shadow war against al-Qaida and its allies.

Most of the attacks by U.S. unmanned aerial vehicles armed with Hellfire missiles are launched from Lemonnier. So are strikes in nearby Somalia against the al-Shabaab Islamist group, which is affiliated with al-Qaida.

But as Islamist forces linked to al-Qaida's arm in North Africa, known as al-Qaida in the Islamic Maghreb, are posing regional threats in Mali and oil-rich Nigeria, while Somali jihadists are attacking Kenya and Uganda in East Africa, a region on the cusp of a major oil and gas boom, the U.S. military is having to look at wider-ranging operations.

Mali is a primary target zone. Jihadists of AQIM and their allies have held all of northern Mali since March and have turned it into a jihadist sanctuary that regional states like Algeria fear will be used to intensify operations against the, destabilizing the region.

An expected offensive against the Mali stronghold will likely be a largely regional affair. But U.S. forces are already quietly setting up in the region with killer drones, particularly in Morocco, a longtime U.S. ally.

U.S .Defense Secretary Leon Panetta declared Nov. 20 the campaign against al-Qaida will be expanded and intensified.

In an address to the Center for American Security, a Washington think tank, he said, "This campaign against al-Qaida will largely take place outside declared combat zones ... using a small-footprint approach that includes precision operations."

Despite the elimination of al-Qaida's "most effective leaders," he warned that the jihadist "cancer" has "metastasized to other parts of the global body" amid fears al-Qaida has exploited pro-democracy uprisings in the Arab world "to gain new sanctuary, incite violence and sow instability."

In April, the U.S. Air Force indicated it was planning to quadruple the scale of the global drone war over the next few years and Camp Lemonnier will be enlarged to conduct a large number of those mainly clandestine operations.

The secret war being run from the base north of Somalia is already expanding.

Published reports state the Pentagon is spending $1.4 billion to enlarge the 500-acre base that already accommodates a squadron of at least a dozen MQ-1 Predator UAVs, a rarely mentioned force of eight F-15E Strike Eagle jets and an undisclosed number of U-28A spy planes.

One of these agile single-engine planes, a militarized version of the Swiss Pilatus PC-12 turboprop, crashed returning from a secret mission in February, killing four Special Forces operators.

The runway at the base, adjacent to Djibouti city's single-runway airport is being extended and revetments for aircraft expanded.

Accommodations for another 1,000 personnel, mostly Special Operations teams is being built, testimony to U.S. plans to step up the secret war.

Other clandestine bases are in the Seychelles, an island state in the Indian Ocean to the east; Ethiopia, a key U.S. ally against Somalia's al-Shabaab; Kenya, gradually being sucked into the counter-terrorism campaign; and in Somalia itself, where the CIA has a base at Mogadishu airport.

Since 2002, U.S. drones, operated by the CIA of the U.S. military's Joint Special Operations Command, have assassinated dozens of top- and mid-level commanders of al-Qaida and associated groups in attacks mostly employing AGM-114 Hellfire missiles.

To give some idea of the scale of the drone campaign, figures compiled by Pakistan's Interior Ministry show that al-Qaida chieftain Abdul Rahman al Zaman Yemeni, killed in a Dec. 1 U.S. drone strike in the Waziristan region, was the 50th senior figure in the organization assassinated in 338 drone attacks since the UAV campaign there began in 2005.

The drone offensive has seriously damaged the jihadist command structure, flexible and resilient as it is, in Pakistan and in Yemen, in the southwestern tip of the Saudi Arabian Peninsula across the Gulf of Aden from Djibouti.

Yemen is a main conflict zone in the battle against al-Qaida.

The drone attacks there, largely carried out by MQ-1 Predators from Lemonnier that are being replaced with deadlier MQ-9 Reapers, have played a crucial role in rolling back an Islamist offensive that seized large areas of southern Yemen in recent weeks.