Scanning Borders, Israel Surveys New Reality of Tunnels and Terror

MOUNT HERMON, Golan Heights — Israel’s military commanders are rethinking their concept of border security as they watch the reality of what is happening on the other side changing in front of their eyes.

With new terrorism, violence and chaos engulfing the Middle East, it is clearer than ever to them that nonstate actors with sophisticated weapons and technology have replaced the threat from Arab armies, forcing Israel to weigh differently the advantages of preventive strikes against the risks of setting off the next war.