African Union soldiers are taking part in exercises ahead of their planned assault on the island of Anjouan in the Comoros.
The beach landing practice on Sunday involving Tanzanian troops was codenamed "Democracy in Comoros".
Some 1,500 African Union (AU) troops are taking part in the operation in support of the Comoros government.
The Comoros government wants to depose renegade Anjouan leader Colonel Mohamed Bacar, whose re-election in June 2007 they regard as invalid.
But South Africa has called for the dispute to be settled by dialogue - and there have been allegations that France does not want Mr Bacar ousted.
Tanzanian African Union troops celebrate at the end of their exercise. The real mission is imminent, say sources.