The United States since mid-June has delivered eight units of the M142 High Mobility Artillery Rocket System, or Himars, which can precisely strike targets within 80 kilometers (50 miles) using the ammunition that has been provided, with plans for four more.

"These systems allowed us to destroy approximately 30 command stations and ammunition storages," Ukrainian Defense Minister Oleksiy Reznikov told the Atlantic Council.

"This has significantly slowed down the Russian advance and dramatically decreased the intensity of their artillery shelling. So it's working. We are grateful to our partners," he said in a virtual appearance at the Washington think tank.

But he said that far more systems were needed, likening Ukraine's border with Russia to the distance from Barcelona to Warsaw.

"The shield of Europe in Ukraine has the same distance -- 2,500 kilometers of aggressive frontline with the enemy. For an effective counter-offensive, we would need at least 100, I think," he said of the Himars systems.

"That could be a game-changer on the battlefield in that case."

He renewed a call for longer-range rockets -- 100 to 150 kilometers (60-90 miles) -- to cut off Russian units from their support.

"We don't need the strategy of the meat-grinder," he said.

President Joe Biden's administration has refused to send longer-range ammunition, fearing that Ukraine would strike targets inside Russian territory and potentially expand the war to a direct clash with the West.