Why Ukraine's Patriot missile systems can't cope with Russia's old, iron bombs

• Russia's air-dropped bombs are a major threat to Ukraine's soldiers and civilians, said military experts.
• The heavy airplane bombs are "particularly vexing" for air defense systems built to strike lighter targets. 
• Modified "glider" bombs have been fitted with GPS systems.

Russia's Soviet-era airplane bombs present a lethal challenge to Ukraine because they are difficult to intercept even using the most advanced air defense systems,  military experts say.