Why is Israel targeting Lebanon's bridges?

An Israeli air strike damaged the Qasmiyeh bridge on Sunday, one of the main routes linking the south to central Lebanon, near the coastal city of Tyre.This comes after Israel's defence minister, Israel Katz, said in a statement that Israeli forces had been instructed to destroy the crossings over the Litani river that were being used by Hezbollah to send reinforcements.Many Lebanese people fear that Israel is attempting to cut off the south of Lebanon from the rest of the country ahead of a possible large-scale invasion, and that displaced families may not be able to return to some of those areas.More than a million people have been displaced, which could lead to a major humanitarian crisis.The BBC's Middle East correspondent Hugo Bachega reports from Lebanon.More on this story here.