Kharkiv's mayor says at least three people have been killed and another 17 injured in Russian strikes overnight.

Former Rep. Chris Stewart, a former fighter pilot, says the U.S. isn’t prepared for this change in modern warfare.

The attack on Friday, which killed at least four people nationwide, came two days after Russia vowed retaliation for an audacious drone assault on its strategic bomber bases.

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

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.

Drones are “ubiquitous, because they are quite useful, and they're demonstrating that every day in Ukraine,” one analyst told NBC News.

Ukraine said its “Operation Spiderweb” attacked Russian warplanes worth hundreds of millions of dollars, utilizing drones that each cost under $1,000 and were launched from wooden containers carried on trucks.

Volodymyr Zelenskyy said the Russian truck drivers who transported what would become platforms for Ukraine's drone attack on Russian warplanes did so unwittingly.

At least three were killed and 49 injured in a missile-and-drone attack that focused on Kyiv, days after a daring assault on Moscow’s bomber fleet.

Though the knock-on effects are unclear, some military commentators have called the strike Russia's "Pearl Harbor." Hopes for direct peace talks, which resumed Monday, remain low.