The Israeli military began building a seven-metre-high cement wall on Monday that will run several miles along the border with Lebanon.
An Israeli security fence already runs along the entire border but the military said the barrier had to be bolstered to protect newly built blocks of flats in the Israeli town of Metulla from sniper fire emanating from the Lebanese village of Kila.
Colonel Amit Fisher said that the wall was "intended to prevent firing from the Lebanese side into the Israeli side. In the past year and a half there have been a number of incidents."
Israel and Lebanon are technically at war but a ceasefire has largely been maintained along the frontier since Hezbollah-led resistance forces fought the invading Israeli army to a standstill in 2006.
An Israeli wall designed to prevent suicide attacks inside Israeli cities already cuts deep into the occupied West Bank. The World Court has deemed that barrier illegal.