The United States is building a ring of secret military bases in the Horn of Africa and the Arabian peninsula as it steps up the use of unmanned drone aircraft to strike at groups linked to al-Qaeda.
A base has been built on the Indian Ocean island chain of the Seychelles, according to leaked diplomatic cables.
Another is being established in Ethiopia, the Washington Post reported.
The US has been launching assassination missions in Somalia targeting the Islamic militant group al-Shabaab, which publicly supports al-Qaeda, for some time.
Washington already has a base in neighbouring Djibouti. Drones were used in two days of attacks near the Shabaab-controlled port city of Kismayo in southern Somalia last week.
Unconfirmed reports suggest that up to 26 people were killed.
The new bases are part of a ramping up of the counter-terrorism campaign in Yemen and Somalia and there are claims that another secret base is under construction in an unnamed country in the Arabian peninsula.
"Ocean Look" - the US operation on the Seychelles - had been billed as an anti-piracy venture, with local media invited to an open day to see one of the drones.
But secret discussions between the Seychelles Government and US officials, revealed in diplomatic cables released to the WikiLeaks website, show the drones were also intended for counter-terror operations.
At one meeting, Seychelles President James Michel invited Washington to see the archipelago as "an aircraft carrier in the middle of the Indian Ocean without the planes".
The cables say both sides "stressed the sensitive nature of this counter-terrorism mission" and pledged not to discuss it outside the highest government circles. When the subject of using the drones as an "offensive weapon" was brought up the US was told that Michel was not "philosophically opposed" but insisted that any such move be discussed with him only.
So-called "hunter killer" drones have become a mainstay of US operations in Afghanistan and Pakistan's border areas, but while there is blanket congressional approval for their use in these countries, the new campaign is aimed at suspected groups in Yemen and Somalia.
The alleged presence of a US base on Ethiopian soil would further strengthen the Addis Ababa Government's position, said Roger Middleton, a regional analyst with the Chatham House think-tank. "There is a danger that a war prosecuted in Somalia exclusively with drones will disengage the US from finding a political solution. If you can control the threat that way, you have no incentive to build a sustainable solution."