The Home Front Command on Wednesday was preparing for a massive military drill next week, to focus on coping with chemical weapons attacks. The nationwide exercise will drill the civilian population as well as military and emergency services.

The exercise was originally scheduled to take place three weeks ago but was postponed due to tension with Syria. The simulation, which is being run in conjunction with the emergency response services, starts Sunday morning as Prime Minister Benjamin Netanyahu announces a week of national emergency preparedness.

Head of the Home Front Command Maj. Gen. Eyal Eisenberg said Tuesday 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 a carrying capacity of hundreds of pounds,” he said.

The drill will include preparation for possible missile strikes against Israel, particularly in the greater Tel Aviv area. The first few days will center on protecting civilian populations at public institutions and private households. Two alarms will be sounded on Monday, at 12:30 p.m. and 7:05 p.m., and citizens will be requested to go to protected rooms or bomb shelters and to stay inside for 10 minutes.

The drill will mark the first time an entire network of early warning systems will be tested. In addition to sirens, civilians are to receive alerts from various sources, including from cellphones, social networks, and the television.

Home Front Defense Minister Gilad Erdan warned Tuesday that rockets raining down on densely populated areas in Israel “are only a matter of time” and could happen at any moment. He referred to the threat posed to Israel by Syria and Iran’s unconventional weapons stockpiles.

“The question is no longer will rockets be fired at the large populated areas in Israel, the question is when it’ll happen,” Erdan told reporters during a briefing ahead of a large drill in southern Israel on Wednesday. He said the battles being fought no longer distinguish between the front line and the home front, as missiles and rockets allow strikes far from the battlefield.

Israeli jets reportedly struck sites near Damascus twice earlier this month, aiming to stop the transfer of advanced Fateh-110 missiles to the Lebanese terror group Hezbollah. Although Israel never took official responsibility for the strikes, it has said it will continue to act to stop weapons transfers and an unnamed official even reportedly threatened to topple the regime in Damascus should President Bashar Assad hit back at Israel for any further strikes. Syria, for its part, has threatened to retaliate if it is hit again.

Earlier this week, the UK’s Sunday Times reported that Damascus put a number of advanced weapons on standby to strike Israel, should Jerusalem hit targets inside Syria again. According to the report, satellite images show Syria has readied its stock of Tishreen missiles for use against Tel Aviv.

US Secretary of State John Kerry stated recently that “strong evidence” exists that the Syrian regime 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 chemical weapons had been used against them.

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.

Joshua Davidovich contributed to this report.