Ukrainian President Volodymyr Zelensky said Tuesday that decisive action must be taken before the U.S. presidential election in November to repel Russia's offensive against his country, using an address on the sidelines of the NATO summit to press for greater support during a pivotal but tumultuous stretch in America's political calendar.

"It's time to step out of the shadows to make strong decisions to act and not wait for November or any other months to descend. We must be strong and uncompromising all together," Zelensky said.