Zelensky said he warned allies that the counter-offensive would proceed slowly amid the wait for weapons.

President Volodymyr Zelensky of Ukraine said he had warned the United States and other Western countries that the counter-offensive would progress slowly as the allies took longer to deliver the promised weapons and ammunition needed for the mission.

In an interview with CNN aired on Wednesday night, Mr. Zelensky said Ukraine had wanted to start the military campaign earlier but had to wait for the advanced weapons.

“I am grateful to the US as the leaders of our support, but I have told them, like the European leaders, that we want to start our counter-offensive sooner, and for that we need all the weapons and equipment,” he said. said through an interpreter.

“Why? Simply because if we start later, it slows down.”

The slow progress is a common fact of allies and pro-Russian military bloggers assessing the counter-offensive, which has been met with extensive Russian defenses.

General Mark A. Milley, Chairman of the Joint Chiefs of Staff, said last week that Ukrainian forces were “advancing steadily and deliberately.”

“Slow advance is very deliberate,” the general added Friday to the National Press Club in Washington.

He said he was not surprised that the long-awaited attempt to retake Russian-held territory did not advance as quickly as many pundits had predicted.

“It’s going to be a very long time and it’s going to be very, very bloody, and nobody should be under any illusions about that,” General Milley said. “Ukrainian soldiers are attacking through minefields and in the trenches, and this is literally a fight for their lives. So yes, sure, it’s a bit slow, but that’s the nature of war.”

Ukraine has yet to deploy most of its reserves, including troops trained in Europe over the winter and spring and equipped with weapons from NATO countries, meaning it can deploy even more force.

In the CNN interview, Mr. Zelensky made a well-known case for even more advanced weaponry and for American-made F-16 fighter jets.

“In some directions, we can’t even think about launching the counter-offensive,” he said, “because we don’t have the relevant weapons.” And to let our people be killed by long-range Russian weapons would be simply inhumane.”

Eric Schmitt And Andrew E. Kramer reporting contributed.