Mali has allowed Algeria to pursue Islamic terrorists across their mutual border, into Mali. The border is largely desert and thinly populated, so the risk to Mali civilians is small when these cross border pursuits do occur. Mali made this offer in response to the June 30 ambush of an Algerian police patrol. In the past, Algeria has not even asked for this kind of "hot pursuit" capability.
Algeria is getting more cooperation from its southern neighbors (Mali, Mauritania and Niger) because of the Algerian Islamic terror groups that are now operating on both sides of the border. Of particular concern for Mali, Mauritania and Niger is the fact that the Islamic militants have lots of money (from Islamic charities or criminal activities like drug smuggling and kidnapping). Of particular concern is how the al Qaeda groups offer to buy foreign kidnap victims from local tribes, and then use their better international connections to get a large ransom. The local tribes have long stayed away from kidnapping, because their villages and families are vulnerable to government retaliation. But the Islamic terrorist groups are just a bunch of heavily armed guys living rough out in the deserts and mountains. Just take their money and leave them alone. But this makes it more lucrative to grab foreign visitors, and this has ruined the tourist trade in northern Mali, Mauritania and Niger.
June 30, 2010: Near the Mali border, vehicles carrying eleven police were ambushed by al Qaeda gunmen. All eleven policemen were killed. Their weapons and equipment were stolen. This was the worst Islamic terror attack in Algeria so far this year, and is indicative of how the terrorists have been driven out of the populous north, and driven into the southern deserts.