The war with Russia is in a new stage, with winter expected to complicate fighting after a summer counteroffensive that failed to produce desired results due to enduring shortages of weapons and ground forces, Ukrainian President Volodymyr Zelenskyy has said.

"We have a new phase of war, and that is a fact. Winter as a whole is a new phase of war," Zelenskyy said in an interview with The Associated Press.

He said despite setbacks, Ukraine won't give up.

When asked whether he was satisfied with the results of the counteroffensive, he gave a complex answer.

"Look, we are not backing down, I am satisfied. We are fighting with the second (best) army in the world, I am satisfied. We are losing people, I'm not satisfied. We didn't get all the weapons we wanted, I can't be satisfied, but I also can't complain too much," the president said.

He gave a frank appraisal of the last summer's counteroffensive.

"We wanted faster results. From that perspective, unfortunately, we did not achieve the desired results. And this is a fact," he said.

According to him, Ukraine did not receive all the necessary weapons from its allies, and limitations in the number of armed forces did not allow them to quickly go on the offensive.

"There is not enough power to achieve the desired results faster. But this does not mean that we should give up, that we have to surrender. We are confident in our actions. We fight for what is ours," Zelenskyy said.

He said Ukraine managed to achieve small territorial successes in the fight against a better armed and fortified enemy.

In addition, the power of Moscow's Black Sea Fleet has diminished after Ukrainian attacks that breached the air defense system and struck its headquarters in occupied Crimea, Zelenskyy said.