Israel has a layered air defence system, which has acted to protect the country from the latest wave of incoming missiles from Iran.    The more well-known Iron Dome brings down frequent incoming short-range rocket systems fired at Israel by both Hezbollah and Hamas. David's Sling, and Arrow 2 and 3, are built to tackle medium-range and long-range ballistic missiles, but how does Israel's defence system work?   Niall Paterson sits down with Sky's military expert Professor Michael Clarke to learn more about the range of defences.  Producer: Alex Edden Editor: Philly Beaumont