Ukraine’s shock drone strike on Russia’s strategic bomber fleet this week has generals and analysts taking a new look at threats to high-value United States aircraft at bases in the homeland and abroad – and the situation is worrisome.

Four people were killed and more than 50 injured in Ukraine after Russia pummeled targets across the country with drones and missiles for a second straight night.

Officials say Ukraine was under an ongoing Russian ballistic missile and drone attack early Friday that wounded at least three people.