A、To control Kidal airport. B、To protect the town. C、To protect the capital Bamako. D、To fight against Islamist militants. B细节推断

French forces say they have entered Kidal in the north of Mali, the last major town they have yet to secure in their fight against Islamist militants. French forces now control Kidal airport after a number of aircraft, including helicopters, landed there last night. Islamist militants were reported to have already left the town and it was unclear who was in charge. France—the former colonial power in Mali—started a military operation this month after Islamist militants appeared to be threatening the south. French army spokesman confirms that "French troops were arranged overnight in Kidal". One regional security source told the Press that French aircraft had landed at Kidal and that protection helicopters are in the sky. Kidal, 930 miles north-east of the capital Bamako, was until recently under the control of the Islamist militants.
1. What is the situation now in Kidal according to the news?
2. Why did the French start the military operation?