Israel and Hezbollah accelerated their cross-border attacks overnight into Sunday with their leaders exchanging saber-rattling threats in a rapidly deteriorating situation that has the adversaries as close to full-out war as they have been in their nearly yearlong conflict.

The latest uptick stoked fear of a broader war in the region. Hezbollah’s response came after a week in which Israel carried out a series of audacious attacks, killing some of the group’s top commanders.