The US Embassy in Israel on Saturday warned Americans there to avoid large gatherings and be prepared to seek shelter following an escalation of conflict in the country.
"The security environment is complex and can change quickly," the embassy said in an alert posted on its website. "Be aware of your surroundings."
The warning came as the Israeli army said it was attacking Hezbollah targets in Lebanon in a second wave of strikes, after intercepting rockets fired from across the border earlier in the day.
