Air raid sirens wailed across Israel on Monday morning and again on Monday evening, alerting the population to scramble to shelters as part of a massive military drill focusing on coping with chemical weapons attacks. The week-long nationwide exercise, code-named “Home Front Eitan 1,” is drilling the civilian population as well as military and emergency services for a possible war in which missiles will rain down inside Israel, primarily from Syria and Lebanon.

The exercise featured two sirens: at 12:30 p.m. and at 7:05 p.m. The IDF Home Front Command, which is organizing the drill, said that people should wait for 10 minutes in sheltered areas before emerging and resuming their day.

The first siren was aimed at drilling civilians in finding appropriate safe areas during their workdays. Schools across the country also took part in the exercise, with pupils heading from classrooms to shelters.

The second siren was meant to catch people at home, where they were also requested to retreat into sheltered areas.

The drill marked a first test for a new network of early-warning systems. In addition to sirens, civilians were receiving alerts from various sources, including cellphones, social networks, and the television.

The exercise was originally scheduled to take place three weeks ago, but it was postponed due to tension with Syria.

On Sunday night, Lebanese media reported that a missile was fired from Lebanon at Israel. The missile apparently exploded near the town of Metulla, where there were no reports of injury or damage.

All areas of the country were included in the drill, with the exception of communities located close to the Gaza Strip. Residents of those areas, who have endured years of relentless rocket fire from Gaza, protested to the Home Front Command that putting their children through a traumatic exercise was unfair. In response, the IDF agreed to exclude their communities from the practice run.

In some areas a different siren sound was tested to indicate a possible chemical weapons attack, Yedioth Ahronoth reported Monday.

According to a map on the Home Front Command website, in the event of a rocket attack from the north, the Tel Aviv and Gush Dan area can expect up to two minutes’ warning, as opposed to just a minute and a half in Jerusalem. The further north a community, the less warning it will get, and those on the border with Lebanon and Syria will have only seconds to run for cover. 

The head of the IDF’s Home Front Command, Maj. Gen. Eyal Eisenberg, said last week that the outbreak of a war in which Israel would be hit with a “large volume of rocket fire” was a certainty. “Our opponents hold long-range missiles with large warheads and the capacity to carry hundreds of kilos,” he said.

“We are not angling for war with Syria, but it’s not only up to us,” Home Front Defense Minister Gilad Erdan told Channel 2 on Saturday.

“There is no change in Israel’s policy toward Syria,” said Erdan, echoing Defense Minister Moshe Ya’alon’s statement from earlier last week that Israel was not interested in interfering in the Syrian civil war, but would retaliate for Syrian attacks and do everything in its power to prevent Syrian weapons from reaching Hezbollah forces.

Asked about the possibility of Syria attacking Israel with chemical weapons, Erdan said that though there was a higher chance of that happening than in the past, it was still considered a “low-probability scenario.”

“Our enemies realize that the use of chemical or nonconventional weapons will draw a devastating response, and the IDF’s capabilities are well-known,” said Erdan.

US Secretary of State John Kerry spoke recently to “strong evidence” that the Syrian regime had used chemical weapons against its people. Kerry’s comments came the same day that Turkish Foreign Minister Ahmet Davutoglu cited tests on Syrian war casualties being treated in Turkey that indicated they had been attacked with chemical weapons.

Damascus’s large stockpile of chemical weapons, and President Bashar Assad’s refusal to sign international accords banning them, has become a major international concern as the civil war in Syria rages on.