Also on Thursday, Israeli citizens were warned by the country's defence ministry that they should stockpile food and water and prepare themselves "for all possibilities".
The emergency mobilisation of reservists to staff the US-made Patriot batteries and Israel's own surface-to-air Hawk missiles was made by Israeli public radio.
"
The chance that something will happen here is very low but we have to prepare for all possibilities
"
Defence ministry head Amos Yaron
During the 1991 Gulf War, Iraq fired 39 conventionally armed Scud missiles at Israel, and Israelis fear that Baghdad could unleash more - possibly carrying chemical or biological warheads - if it is attacked by the United States.
In an interview with the Maariv newspaper, defence ministry director-general Amos Yaron said that Israel's anti-aircraft and missile defence system - including the Israeli-made Arrow missile killer - would be fully operational by 15 February.
Stockpile supplies
Later Mr Yaron told Israel Radio that citizens should start to follow instructions in a recently-distributed emergency handbook that explains how to seal rooms against chemical or biological attack.
The handbook also advises them to stock up on food, water, batteries and first aid kits.
"The chance that something will happen here is very low but we have to prepare for all possibilities," he said.
Hardware shops in Israel have reported heavy demand for plastic wrap and heavy-duty tape to seal rooms, the Reuters news agency said.
On Friday, UN head weapons inspector Hans Blix is due to present his latest report to the UN Security Council on whether Iraq is adhering to resolutions requiring it to dismantle its alleged weapons of mass destruction.
The United States, which has vowed to disarm Iraq by force if needed, has already begun evacuating non-essential staff and diplomats' families from its embassies in the Middle East.