Oh yeah, send in the UN...considering every major UN intervention has the troops there either looking feckless and helpless (The Pakistani experience in Somalia or the UN peacekeeping force in Lebanon) asking the UN for help is kinda pointless, but me thinks the Arab League is probably asking them as they know what the other alternative is...Israel or Turkey ends this pretty soon on their own accord.
Israel doesn’t want this spreading into Lebanon, and Lebanon’s pretty fragile politically right now. There’s already been some early fighting on their side of the border, and Lebanon does have a history, as well as their major backer is falling apart fast. What happens when all that comes apart? The Israelis will be left with some very unpalatable options.
Lebanon isn’t politically fragile, there is no Lebanese gov’t per se because of the Iranian proxies that occupy part of the country. Syria has its fingers in to some extent but Syria’s troops were finally pulled out due to pressure by the Lebanese and the international community, after thirty years of Syrian occupation of part of the country. The number of Lebanese who aren’t anti-Israel is small on a good day; a partitioned and divided Lebanon has led to years of attacks, while the unity Christian/Muzzie regime prior to the mid-1970s meant a quiet border. That regime was destroyed by the PLO.