UNITED NATIONS (AP) — Secretary-General Ban Ki-moon said Friday that France, Senegal and Nigeria have responded to an appeal from Mali’s president for help to counter an offensive by al-Qaida-linked militants who control the northern half of the country and are heading south.

The U.N. chief said in an interview with The Associated Press that assisting the Malian defense forces push back against the Islamist armed groups is “very important.” The militants captured the city of Konna on Thursday, and were threatening the city of Mopti, which has 100,000 inhabitants.