Africa's Gulf of Guinea nations lack the means to tackle mounting threats from piracy and kidnappings while the United States, a major buyer of their oil, is restricted in its efforts to help them.
Here is a list of some of the attacks that have taken place in the Gulf, which stretches from Angola to the south, around Africa's central and western coast, to the Guineas in the west.
17 Feb, 2009 - Seaborne gunmen attacked oil-producing Equatorial Guinea's island capital, shooting their way into the presidential palace before they were repelled by the security forces, backed by helicopter gunships. The government blamed militants from Nigeria's Niger Delta for the raid.
December, 2007 - Armed raiders in speedboats stormed two banks in Bata, grabbing cash and shooting passers-by.
BAKASSI PENINSULA -- CAMEROON/NIGERIA BORDER
14, March, 2009 - Gunmen attacked a supply vessel contracted to Royal Dutch Shell, kidnapping one Ukrainian and three Filipino crew off the coast of Bakassi, on the Nigeria-Cameroon border.
31 Oct, 2008 - Gunmen saying they objected to the return of the Bakassi peninsula to Cameroon seized 10 crew, most of them French, working on an oil supply vessel.
19 Oct, 2008 - Cameroonian security forces fought off an attack by pirates in the waters off the Bakassi peninsula.
11 June, 2008 - Pirates ambushed and abducted a Cameroonian official and five soldiers.
24 Jan, 2009 - About 30 armed pirates seized a Greek fishing vessel off Kribi, killing a Greek sailor in the process.
28 Sept, 2008 - Gunmen attacked the Cameroonian port town of Limbe, shooting their way into banks, killing one person as they fought off the security forces and made off with large amounts of money.
4 Jan, 2009 - Gunmen hijacked a vessel belonging to French oil services group Bourbon off Nigeria's Niger Delta as it traveled toward a Royal Dutch Shell offshore oilfield with four expatriates.
This attack followed a June 2008 strike against Shell's $3.6 billion offshore Bonga oilfield that forced the plant, which has a capacity of 220,000 barrels per day, to shut down.
(Writing by David Lewis; Editing by David Clarke)