Aren't you reducing to the point of amalgam the situation in Mali? Is the secessionist state even existing other than on paper?
Not denying that salafist/islamist groups are taking advantage of the situation in the north, including "AQ for Islamic Maghreb", but the situation has a long history and is currently so confused I would be cautious of any judgement. I haven't seen a single comprehensive article on the situation that would leave me less confused. But maybe you have better sources: it would interest me.
Besides, let's not fool ourselves: apart from sanctioning a milita... sorry "peacekeeping" operation, what could the UN realistically achieve?
- There's no legit government in Bamako and the junta does not seem to cooperate despite the fact they agreed to step down. There's been reports of gunfights in Bamako between army units in the first days of May.
- Even if there was one, the regular army of Mali was unable to defend the northern half of the country and started retreating before the putsch. Unless it was all a massive blunder, it doesn't seem reasonable to expect they could regain control of the whole country alone.
- Regional diplomatic efforts are constantly failing, and the powers concerned in the area does not seem to agree on the course of action to follow. Algeria is accused (in Malian news sources) of not cooperating, to have provided a safe haven to rebel tuareg groups and even by some to be supporting those. French President Sarkozy said (during the presidential debate) that "Algeria had all the keys to the problem" which I guess is a way to imply they are not doing enough. Anyway, Algeria has not agreed to provide any sort of military help. Do note that 7 algerian diplomats stationed in Gao are held hostage by a splinter islamic group.
- I don't think a lot of powers are comfortable with either a "Tuareg" or "Islamic" splinter state here, but maybe I am mistaken. West African geopolitical issues are not my forte. But maybe everyone will decide to settle for the partition of the country...
Pretty good odds of a French military intervention under UN mandate in the next six months, I'd say, esp. if the situation worsens.