Why is Israel pushing towards the Litani River in southern Lebanon?

Israel has launched a ground invasion into southern Lebanon, declaring its intent to push Hezbollah back 30 kilometres beyond the Litani River. This move follows the killing of over 1,000 Lebanese people and the displacement of 1 million. The strategic importance of the Litani River raises questions about the long-term consequences of Israel's invasion — for Lebanon and the region as a whole.