JERUSALEM — A joint US-Israeli missile interceptor meant to counter the type of medium-range missiles possessed by Iranian-backed Hezbollah militants became operational Sunday, completing Israel’s multilayer defense system amid tensions on its frontiers with Syria and Gaza.

Prime Minister Benjamin Netanyahu said at the unveiling ceremony for the David’s Sling system that defending the home front is of the ‘‘utmost importance.’’ He went on to warn ‘‘whoever tries to strike us will be hit, those that threaten our existence put themselves in existential danger.’’

David’s Sling marks the completion of Israel’s multitier system that includes the Arrow, designed to intercept long-range ballistic missiles in the stratosphere with an eye on Iran, and Iron Dome, which defends against short-range rockets from the Gaza Strip.

David’s Sling was developed by Israeli defense firm Rafael with American defense company Raytheon.