West African nations have a long history of sending their military forces to intervene in neighbouring countries, under the umbrella of a regional cooperation bloc.

Created in 1975, the Economic Community of West African States (ECOWAS) focuses mainly on resolving regional conflicts.

In the case of The Gambia, where ECOWAS has temporarily suspended a military operation, the bloc has thrown its support behind the new President Adama Barrow.

The group has 15 members, of which eight are francophone (Benin, Burkina Faso, Guinea, Ivory Coast, Mali, Niger, Senegal and Togo), five anglophone (The Gambia, Ghana, Liberia, Nigeria and Sierra Leone) and two Portuguese speaking (Cape Verde and Guinea-Bissau).

The organisation is dominated politically and economically by regional powerhouse Nigeria.

Here's a look at the five main foreign interventions carried out since 1990:

- Mali -

On January 11, 2013, following a UN Security Council resolution, the bloc authorises the immediate deployment of an intervention force aimed at helping Mali retake its Islamist-controlled north.

The same day, the French military launches Operation Serval to back the Malian army and drive back the Islamists, who are pushing south towards Bamako.

The West African force comprises 6,300 men, including 2,000 from Chad, which is not an ECOWAS member. The Chadian soldiers were on the front line alongside French soldiers in fighting the insurgents.

On July 1, 2013, the ECOWAS force is absorbed by the UN's MINUSMA stabilisation force in Mali, which is currently 13,000 strong.

- Guinea-Bissau -

West African troops are deployed in May 2012 to help the political transition after one of the nation's many coups.

They have since served with a mandate to protect public figures and institutions.

The force consists of more than 600 police officers and paramilitary gendarmes from Nigeria, Burkina Faso, Niger, Senegal and Togo.

Already in February 1999, a lightly armed ECOWAS force was deployed to help resolve the crisis in the insurgency-hit country, but withdrew several months later after failing to prevent a resumption of fighting and the overthrow of the head of state.

- Liberia -

In August 1990, ECOWAS sends a force of several hundred men to Liberia to intervene in a civil war ignited eight months earlier.

The ECOWAS Ceasefire Monitoring Group, or ECOMOG, quickly grows to nearly 20,000 soldiers.

Although generally described as a peacekeeping force, ECOMOG is soon called on to take more responsibilities for maintaining order.

In early 1997, more than seven years after the war started, ECOMOG carries out a major disarmament operation, paving the way for multi-party elections in July.

The last ECOMOG soldiers leave Liberia in October 1999.

In August 2003, a new ECOWAS mission, ECOMIL, is deployed in Monrovia, the capital, which had been under siege by rebels for three months. Restricted to some 3,500 soldiers, the force is unable to deploy across the whole of the country and transfers its contingent to the United Nations.

- Sierra Leone -

ECOMOG's Nigerian contingent drives a 1997-98 military junta, the Revolutionary United Front, from Freetown and reinstates president Ahmad Tejan Kabbah. The RUF later invades Freetown on January 6, 1999, before being expelled two weeks later by ECOMOG troops.

The West African intervention force, which has up to 11,000 men in Sierra Leone, officially winds up its mission in May 2000 and is replaced by the UN peacekeeping force, formed to guarantee the Lome peace accord of July 1999, which ended the civil war.

- Ivory Coast -

A 1,300-strong West African force is deployed in January 2003 after a military rebellion which effectively cuts Ivory Coast in two. In 2004 the soldiers are integrated into the UN's mission in the country.