TEL AVIV—Israel’s military began an operation to destroy tunnels that it said were built by Iran-backed militant group Hezbollah that stretched from Lebanon into the country’s north and could be used to launch attacks against Israeli citizens.
The operation, whose scale Israel didn’t specify, is the latest development in an effort by Israel to counter what it says is a growing threat by Hezbollah on both its Lebanese and its Syrian borders. Israel says it has attacked over 200 Iranian targets in Syria with airstrikes since...