KFAR YONA, ISRAEL, OCT. 7 -- Israeli families tried on gas masks and trooped home with shopping bags full of gear here today as the army launched a massive operation to supply the country's 4.6 million citizens with protection in the event that Iraqi leader Saddam Hussein carries out his threat to attack Israel with chemical weapons.

The distribution began in this bedroom community of 5,000 people northeast of Tel Aviv and in two other small towns so that the army could experiment with procedures for what authorities said was the largest mass distribution of gas masks since World War II. Officials said the nationwide campaign would take up to three months to complete, although there are plans to finish it in three days if necessary.

The decision to hand out the equipment has wiped out Israel's tourism industry and rattled some nerves even in a society accustomed to security crises. Still, most of the families who appeared at a municipal center here this afternoon seemed to accept their gas masks with relative equanimity.

"I don't worry about it because the chemicals are not very effective and Saddam would be crazy to attack," said Sassa Eliah, a 25-year-old student, as he lugged a box holding a special protective tent for his 1-month-old son. "This is just like an insurance."

At the urging of the United States, Israel has tried to maintain a low profile during the crisis in the Persian Gulf, and military leaders continue to say they do not intend to attack Iraq and doubt that Saddam's missiles and bombers can do much damage to Israel. The government initially decided in August to postpone any distribution of gas masks because of concerns that the move would panic Israelis or be seen by Saddam as a provocation.

The decision to proceed with the operation this month appeared to reflect the army's desire to respond to Saddam's continuing threats against Israel as well as to prepare the country for a possible escalation of the crisis.

In a meeting with journalists here today, the army's commander for the central zone of the country, Gen. Yitzhak Mordechai, said that if Israel were compelled to mobilize for war, its men would be able to report to their army units "feeling that their family is protected."

Mordechai said the army's operation amounted to transferring chemical-warfare equipment "from central storage to home storage" and was not an emergency procedure. For that reason, he said, the army would not now distribute masks and other equipment to the 1.7 million Palestinians living in the occupied West Bank and Gaza Strip.

Military officials said last week that Palestinians would be given masks but would be charged the equivalent of $20 for them. Israel does not now have enough masks for the Palestinians but plans to import new supplies from Europe, the officials said.

"In this still-not-emergency situation we are not doing anything" in terms of providing masks to Palestinians, Mordechai said.

The kits handed out by the army here, which were manufactured in Israel, include gas masks; injections of atropine, which is an antidote to nerve gas; and powder that can be used against liquid chemicals. In addition to standard masks, the officials are handing out plastic adjustable masks for children and incubator-like tents for infants.

Israel radio said today that a Jerusalem institute had arranged to import 25,000 masks designed for men with beards. Some Orthodox Jews, it said, are reluctant to shave their beards to use conventional gas masks, even though rabbinical authorities here have decreed that they may do so.