A Qassam rocket launched from northern Gaza Monday evening landed on the coast near Ashkelon, adjacent to an Ashkelon suburb.
There were no casualties as a result of the attack.
Earlier Monday, following a series of security assessment meetings, Defense Minister Ehud Barak instructed the security establishment to allow some basic supplies into Gaza amid mounting international concern over a deterioration of the humanitarian situation in the Hamas-controlled territory.
Thirty-three truckloads of humanitarian and other basic goods were to be delivered to the Strip, a defense ministry spokesman said. A military official said Israeli authorities also opened the Nahal Oz terminal for the delivery of fuel to Gaza's sole power plant.
The Israeli authorities had previously opened the Kerem Shalom border crossing for only one day since a November 4 surge in violence.
'Drip-drip approach won't allow us to function'
The closure of the crossings had led to rising international concern over the situation in the overcrowded sliver of land whose economy has been crippled by an Israeli blockade imposed after the Islamist Hamas movement seized power in June 2007.
With stocks running dangerously low, the UN Relief and Works Agency (UNRWA) had expressed fears it would have to suspend its food distribution for the second time since Israel completely sealed off the territory at the beginning of the month.
The agency welcomed the decision to allow supplies in but said far more is needed.
"It is most emphatically not enough," said spokesman Chris Gunness. "This drip-drip approach will not allow UNRWA to function."
Israel had been expected to ease the blockade when a truce went into effect on June 19, but has cited continuing rocket and mortar fire from Gaza in refusing to do so. Hamas accuses it of failing to keep to its side of the bargain.