Eli Harel was an Israeli soldier in his early thirties when he was sent into Lebanon in 2006 to battle fighters from the Iranian-backed group Hezbollah in a bloody, largely inconclusive month-long war.

Now 50, Harel is ready to rejoin the army to fight the same group if shelling along Israel's northern border turns into a full-blown war with Iran's most powerful regional proxy. This time Israeli forces would face some of the most challenging fighting conditions imaginable, he said.

"There are booby traps everywhere," he told reporters. "People are popping up from tunnels. You have to be constantly on alert otherwise you will be dead."