Ukraine says Russia is holding aid workers captive in Mariupol

Speaking Tuesday night in a video address to his nation, Ukrainian President Volodymyr Zelenskyy accused Russian forces of seizing a humanitarian convoy in Mariupol.

Ukrainian Deputy Prime Minister Iryna Vereshchuk said the Russians are holding captive 11 bus drivers and four rescue workers as well as their vehicles. 

Zelenskyy said the efforts to establish stable humanitarian corridors in Mariupol, which has been under heavy attack, are being "foiled by the Russian occupiers, by shelling, or deliberate terror."

A senior U.S. defense official told the Associated Press that Russian ships in the Sea of Azov are adding to the shelling of Mariupol, a strategic port city.

On Wednesday, Kremlin spokesman Dmitry Peskov said that the Russian military operation is unfolding "strictly in accordance with the plans and purposes that were established beforehand."

He added that Putin's aims are to "get rid of the military potential of Ukraine" and to "ensure that Ukraine changes from an anti-Russian center to a neutral country."