The United States is providing Ukraine with a fresh $1 billion worth of military and civilian security assistance, plus a controversial tank ammunition with depleted uranium.

US Secretary of State Antony Blinken announced the aid during a surprise visit to Ukraine on Wednesday,

In a press conference, Blinken said the aid would further "build momentum" for Ukraine's counteroffensive.

The depleted uranium shells are 120-millimeter rounds for M1 Abrams tanks that are expected to be delivered to Ukraine before the end of 2023.

Depleted uranium munitions, which can pierce tank armor, are controversial due to their association with health problems such as cancer and birth defects in areas where they were used in past conflicts, though they have not been definitively proven to have caused such issues.

"The US is deliberately transferring weapons with indiscriminate effects," Russia's embassy in Washington said Wednesday.

"It is fully aware of the consequences: explosions of such munitions result in the formation of a moving radioactive cloud."

The US decision "is a clear sign of inhumanity," the Russian embassy said on Telegram.

Meanwhile, Russia struck a market in Ukraine's Donetsk region with missiles, killing at least 16 people and wounding dozens others.

Projectiles tore through the center of Kostiantynivka town which has a population of nearly 70,000.

Russian drones also attacked the Danube river port of Izmail for the fourth time in five days, the regional governor said Thursday.

The latest overnight attack, using Iranian-made Shahed drones, lasted three hours, Odesa regional governor Oleg Kiper said on Telegram.

"Civil and port infrastructure facilities, an elevator and an administrative building were damaged."