The American aircraft carrier USS Lincoln, and its crew of 5,300, left Aceh, reducing the number of American military personnel involved in relief work to about 5,000. Another 5,000 left last month, where there were some 15,000 American troops helping out. The US Navy helicopters were critical in the weeks after the December 26 tidal wave. But as roads were restored, truck based transportation became more important. The only downside to the presence of foreign troops in the relief effort, was that it freed up Indonesian troops to keep fighting the Aceh separatists.