The United States has secured a ten-year lease for a key military base in Djibouti that it relies on to launch "counter-terrorism" missions, including drone strikes, in Yemen and the Horn of Africa.
US President Barack Obama and his Djibouti counterpart Ismail Omar Guelleh announced the renewed lease on Camp Lemonnier on Monday as they met at the White House, pledging to counter al-Qaeda and al-Shabab fighters in the region.
Under the agreement, the Washington would pay $63m annually for a ten-year lease, with an option to extend the arrangement for another decade, administration officials said.
The new deal represents a major increase in rent, as the US reportedly pays $38m a year under the current lease.
"Camp Lemonnier is extraordinarily important to our work throughout the Horn of Africa but also throughout the region. We very much appreciate the hospitality that Djiboutians provide," Obama said.
"Overall, this is a critical facility that we maintain in Djibouti, we could not do it without the president's co-operation, we're grateful for him agreeing for a long-term presence there."
Djibouti, a tiny nation of less than one million people, has become essential to US operations in Africa and the Middle East.
Camp Lemonnier houses conventional forces, as well as special forces and aerial drones flown over Yemen and Somalia.
Guelleh said his East African country and the US were linked in a "strategic partnership" to deal with "the fight against terrorism, piracy and human trafficking in our region."
Obama also promised more US assistance and equipment for Djibouti's forces, including for troops deploying to the African Union mission in Somalia.
More US development aid for Djibouti's economy, including help improving the country's electricity network, was also pledged.
After al-Qaeda's attacks on US soil on September 11, 2001, the US presence has steadily increased.
US officials, anxious to maintain a low-profile for its military in Africa, tend to disclose few details about operations at the base.
The Pentagon reportedly has informed Congress of plans for a dramatic expansion of its facilities in Djibouti, proposing more than $1bn in construction projects.