With Iran-backed Hezbollah on the defensive after a series of heavy Israeli blows, the United States and Iran are locked in a showdown over Lebanon's future, analysts said.

Hezbollah, the most powerful regional force backed by Iran, which arms and finances it, has long held sway in Lebanon.

Just a month ago, Dahieh's bustling streets were packed with traffic, families strolling about and youths in cafes, but now silence dominates the abandoned Hezbollah bastion, interrupted only by the sound of Israeli bombs.

Escalating Israeli attacks since late September, after nearly a year of low-intensity cross-border exchanges, have reduced much of the Lebanese capital's once densely-packed southern suburbs to rubble and sent many of its residents fleeing.