"This is not a stalemate; it's a problematic situation," Zelenskyy said.
"A stalemate is a deadlock, but a problem can be solved."
Ukraine's Armed Forces currently have 14 brigades lacking sufficient weaponry because promised Western arms are not arriving on time.
"We don't have the weapons that have already been voted on in the U.S. Congress," he said.
"The aid packages are coming slowly. We are grateful to Congress for their support, but everything needs to arrive."
Ukraine's counteroffensive depends on the delivery of these weapons, and there are no timelines or schedules for such actions at the moment, Zelenskyy said.
"We are ready when the weapons arrive, but they are not here yet," he said.
The delay between the decision to send weapons and their actual arrival is significant, Zelenskyy said, calling it "the biggest tragedy of the war."
U.S. President Biden signed a bill on April 24, providing $61 billion in support for Ukraine. The House of Representatives had been unable to pass this bill for more than six months. Immediately after signing, Biden announced that the U.S. would begin supplying weapons from the next aid package to Ukraine within hours.