Ukraine ready for counteroffensive, but risks heavy losses, says Zelensky. Only one weapon, the US Patriot surface-to-air missile system, can protect Ukraine's skies, he added.

"We don't want to be a member of NATO during the war," he said. "It's too late. But tell me how many lives a sentence is worth at the top of Vilnius?" he said, referring to the NATO summit in Lithuania next month. "I think it is useless for Ukraine to participate in this summit," he told the Wall Street Journal.