Joanna Kakissis

sites in these nations with Shahed drones in retaliation for the war that the U.S.

and Israel is waging on Iran.

Joanna Kakissis, NPR News, Kyiv.

In a video address, Zelensky talked about the Iranian leadership's close ties with Russian President Vladimir Putin and how, during four years of all-out war, Russia has struck Ukrainian cities more than 57,000 times with Iranian-designed Shahed drones.

The Iranian regime chose to be an accomplice to Putin and supplies him with Shahids, Zelensky said, not only with the drones, but with the technology to make them.

Shahids resemble small airplanes and often carry explosives.

The drones buzz like mopeds when they fly into Ukrainian cities, often tearing into apartment buildings.

Russia now produces thousands of these drones every month using Iranian blueprints.

Joanna Kakissis, NPR News, Kyiv.

Speaking to reporters during a private briefing in Kyiv, Zelensky said it was impossible for him to travel to Moscow, adding that it would be just as plausible as Putin coming to Kyiv.

I'm openly inviting him, Zelensky said, if he dares.

Zelensky explained that he's open to meeting Putin on neutral ground.

Zelensky also welcomed President Trump's claim that Putin has promised to stop strikes on Ukraine's energy grid, which has left thousands without power in sub-zero temperatures.

The Ukrainian president said there is no direct agreement between Russia and Ukraine on this issue.

Joanna Kakissis, NPR News, Kiev.

Never thought of it.

We were just doing it for fun, just for the love of terriers, but thinking, yeah, why not?

The report is by the Center for International and Strategic Studies in Washington.

It puts Russian casualties at 1.2 million and Ukrainian ones at up to 600,000.

Of those casualties, the dead are estimated at up to 325,000 Russians and up to 140,000 Ukrainians.