Warsaw and Vilnius are analyzing procedures and logistics for a possible mass evacuation of civilians in the event of an attack.
Authorities plan to add two more mobile shelters by the end of the year as construction continues across the region.
Saudi authorities have declared an all-clear for three of five areas previously placed under a danger alert, while continuing to urge residents to follow civil defense safety instructions.
As Russian strikes on Kyiv intensify, a city official has called for faster deployment of additional mobile shelters to protect residents.
Authorities ended heightened alert status in Jazan, Khamis Mushait and Abha, areas previously placed on alert amid tensions with Yemen's Houthi movement, according to Anadolu Agency.
Civil Defense authorities warned residents to seek shelter indoors and avoid windows and open areas.