Russian forces are intensifying their offensive in eastern and southern parts of Ukraine in the face of fierce resistance from Ukrainian troops.

The head of British intelligence warns that Russia is shifting to a strategy of attrition that will involve what he calls reckless and indiscriminate use of firepower.

People in the eastern city of Mariupol are reeling after days of heavy shelling.

One resident said, "We've had enough... I feel cold and frightened. Nothing can be worse."

Desperate efforts continue to rescue hundreds of people trapped in a theater that was bombed by Russian forces.

Tomas Bendl of Doctors Without Borders said," Hospitals and pharmacies have completely run out of supplies.
There's no possibility to actually provide emergency medical aid. The situation happening in Mariupol will happen in other cities as well."

Civilian casualties are mounting across the country.

The office of the UN High Commissioner for Human Rights confirmed at least 816 deaths as of Thursday. That includes 59 children.

Former director of the US Central Intelligence Agency, David Petraeus, told NHK that maneuvers by Russian military units are being poorly carried out.

Petraeus said, " They've gotten bogged down, and then they're just resorting to use of bombs, rockets, missiles and artillery, many of which are very imprecise and are hitting indiscriminately, civilian infrastructure."

The UN says the number of people who have left the country now stands at 3.27 million... and that nearly a quarter of the Ukrainian population have fled their homes. It says many people stranded in war-torn areas are unable to leave.

Ukraine's President Volodymyr Zelenskyy has released a video message urging Russia to continue with ceasefire talks.

Zelenskyy said, "Negotiations are the only opportunity for Russia to reduce the number of people victimized by its own mistakes. It's time to talk."

On Thursday, Russian President Vladimir Putin spoke by phone with Turkish President Recep Tayyip Erdogan.

A senior Turkish official said Putin reiterated Russia's demands that Ukraine accept a ceasefire, and expressed his intention to hold direct talks with Zelenskyy.