A French defence official admitted today that France is to move surveillance drones to west Africa.
It is holding secretive talks with US officials in Paris this week as it seeks to win back the north of Mali from Muslim Ansar Dine rebels for Mali's new government.
The United Nations has said that any invasion of Mali's north must be led by African troops, but France is playing an increasing role behind the scenes.
Paris fears that northern Mali could become a haven for terrorists.
France is reported to have special forces in the region and to have contracted out surveillance of Mali to a private company.
US and French diplomats began two days of talks in Paris on Monday.
The US sees France as a key player in Mali and a French defence official said the US "has conferred to us the role of leader" in the crisis.
As Aslef's annual assembly of delegates begins in Edinburgh tomorrow the general secretary explains the challenges his members - and workers across the country - face