Ukraine is preparing for any possible attacks from Russia, including the most extreme and worst-case scenario, a nuclear attack.

Authorities in Kyiv started publicly distributing potassium iodine pills to its citizens and issuing safety precautions in the event of a nuclear attack. The city council of Ukraine’s capital also started preparing evacuation centers.

Potassium iodide pills work by saturating the thyroid gland with non-radioactive iodine. This prevents the absorption of radioactive iodine, which can lead to thyroid cancer. The medications are most effective when taken within four hours of radiation exposure.

Last month, the European Commission pledged to deliver 5.5 million potassium iodide tablets to Ukraine as a “preventative safety measure,”, especially for residents living near nuclear facilities like Zaporizhzhia. This was also the time when there was a lot of shelling around the Zaporizhzhia Power Plant, and the UN intervened to ensure the facility’s structure was safe.