Nice daydream. A UN controlled buffer force? HAHAHAHAHAHA!
The UN is pro Hezbollah. What you would see from a UN controlled security force would be the same as we have seen over the years with UN observers enforcing resolution 1559, who somehow didn't notice iran's militita setting up and stockpiling rocket launchers throughout southern lebanon.
It's plain to see that the UN not only FAILED to implement UN resolution 1559, they purposely looked the other way and allowed Hezbollah to establish and strenghten their presence in Lebanon after the Israeli pull out. During that time, they also cleanzed even more Christians out of Lebanon, on top of the 20,000 they massacured in the 70's, with the aproval of the democrat party under Carter.
"UN observers enforcing resolution 1559"
UN "observers" can't "enforce" anything. A mandated UN force with enforcement powers and weapons can.