By Nick Childs
BBC world affairs correspondent
A Nato task force of ships from six nations has been conducting operations off the coast of Somalia, where there has been a upsurge in piracy this year.
The ships - from Denmark, Portugal, the Netherlands, Canada, Germany and the US - are on the first circumnavigation of Africa by a Nato naval group.
They have been collecting information and building up a maritime picture.
The aim is to ensure that Nato will be better prepared if it has to conduct naval operations there in the future.
The task force will then be heading into the Red Sea and the Mediterranean.
The waters off Somalia and the Horn of Africa are a region where there has been particular concern about maritime security.
The London-based International Maritime Bureau (IMB), which monitors these things, reported a dramatic new increase in piracy off Somalia in the first half of this year.
The IMB's director, Capt Potengal Mukundan, welcomed the arrival of the Nato ships, but said what was needed was a sustained presence in the area.
Just over a month ago the Nato force began its circumnavigation of Africa - a first for the alliance.
The ships sailed down the west coast, and conducted operations in the Gulf of Guinea - another area of concern.
They also took part in what Nato called "highly successful" exercises with the South African Navy - an emerging regional maritime power.
The Nato deployment is further evidence that the alliance is seeking to adopt a broader security mission beyond its old Cold War role, and that the major Western powers are taking a new and increasing interest in the security issues in and around Africa.