"Given the scale of the war and Russia's unwillingness to accept the reality and withdraw from Ukraine, we will need to fight through the winter," Foreign Minister Dmytro Kuleba told a news conference in English.

"The best way to protect our civilians from Russian terror is to defeat Russia."

He spoke from a bomb shelter in the Ukrainian capital Kyiv as air sirens sounded throughout the country.

Kuleba said Ukraine needed more air defence systems, ammunition and armoured vehicles.

He said it was also "very important" for his country to receive more 155 mm artillery cannons and ammunition.

"Ukraine needs more cannons to be able to stop the Russian offensives and to continue with its own counter offensives," he said.

On Tuesday, Ukraine's Western allies pledged an additional one billion euros ($1.1 billion) in emergency winter aid, responding to pleas from President Volodymyr Zelensky for help to withstand Russia's onslaught on its energy grid.

Failing to make an impact on the battlefield, Moscow has switched tactics since October when it began air strikes on the energy network, plunging millions into cold and darkness in winter.

Kuleba said Ukraine had seen six "massive strikes since October 10".

"Such barbarism is Russia's response to losing the war on the battleground. They have suffered a number of humiliating defeats," Kuleba said.

"Russian missile terror will not break Ukraine down," he added.