Complex sentence: British forces in Sierra Leone were operating on the authority of the Sierra Leone government, but President Ahmad Kabbah allowed British forces to conduct the negotiations themselves, as it was apparent that his government lacked the requisite expertise.
Split into simpler sentences: British forces in Sierra Leone were operating on the authority of the Sierra Leone government. However, President Ahmad Kabbah allowed British forces to conduct the negotiations themselves, as it was apparent that his government lacked the requisite expertise.