Sweden on Monday began sending about five million leaflets to residents urging them to prepare for the possibility of war, as neighboring Finland launched a new preparedness website.

In January, Sweden’s former commander-in-chief General Micael Bydén said openly: Swedes should mentally prepare for the possibility of war. In March, Sweden formally joined NATO as the 32nd member of the transatlantic military alliance, almost a year after Finland.

The updated Swedish guide explains how to react to an attack with nuclear, chemical or biological weapons: “Take cover in the same way as in an air attack. Shelters provide the best protection. After a couple of days, the radiation has decreased significantly.”

“It’s no secret that the security situation has deteriorated since the previous brochure was issued in 2018,” Civil Defense Minister Carl-Oskar Bohlin said at a press conference last month. The Swedish Baltic Sea island of Gotland is little more than 300 kilometers (186 miles) from the Russian enclave of Kaliningrad.

Since the start of the war between Russia and Ukraine, Stockholm has repeatedly urged Swedes to prepare both mentally and logistically for the possibility of war, citing the serious security situation in its vicinity.

In Finland, which shares a 1,340-kilometer (832-mile) land border with Russia, the guide is compiled by the government, which has emphasized that “preparedness is a civic skill in the current global situation.”

The Nordic countries urge all people to store drinking water, canned food, medicine, heat, toilet paper, money and flashlights and candles. And if possible, keep the car full of gas.

The checklist also includes iodine tablets, in the event of a nuclear incident.

With input from agencies.