BERLIN — NATO Secretary General Jens Stoltenberg has warned that the war in Ukraine could be long, as Kyiv’s counteroffensive against Russia continues to make only marginal gains.

Ukraine’s allies have sought to accentuate campaign gains in recent weeks, but it has been under way for months with no major breakthroughs. The fall will bring changing conditions on the ground and the possibility that Russia will once again try to pummel Ukrainian energy infrastructure.

“Most wars last longer than is expected when they first start. Therefore, we must prepare ourselves for a long war in Ukraine,” Stoltenberg said in an interview with German newspaper Berliner Morgenpost published Sunday.

“We are all wishing for a quick peace. But at the same time, we must recognize: If President Zelensky and the Ukrainians give up the fight, their country would not exist anymore. If President Putin and Russia laid down their weapons, we would have peace,” the NATO chief said.

“The easiest way to end this war would be if Putin withdrew his troops,” he added.

On the possibility of Putin using nuclear weapons in Ukraine, Stoltenberg said: “Putin’s nuclear rhetoric is dangerous and ruthless, but NATO is prepared for every threat and challenge.

“The point of NATO is to prevent war — not least nuclear war. We have a credible deterrent.”

The NATO chief reiterated that it is just a matter of time before Ukraine joins the alliance.

“Ukraine will become a member of NATO — all allies have made that clear,” he said, adding that Ukraine will need safety guarantees when the war ends, otherwise “history could repeat itself.”

Addressing the idea of a possible nuclear threat by the Russians, Stoltenberg said: “We have sent a clear message to Russia: A nuclear war cannot be won and must never happen. Moscow must understand that the use of nuclear weapons is unacceptable.

“We are observing very closely what the Russian army is doing. Until now we have not noticed any changes to Russia’s nuclear forces that would prompt us to react.”

Ukraine has made only incremental gains against Russia in its counteroffensive so far and the wins have come at great cost.

On Friday, Ukrainian troops announced they had retaken the village of Andriivka, south of the city of Bakhmut, the first such announcement of a recaptured settlement for several weeks.

The clock is ticking for Ukraine to make a significant gain, with the fall bringing worsening weather and even more challenging fighting conditions.

The United States’ top general believes Ukraine has just six weeks left before changing weather hampers its counteroffensive.

“There is still a reasonable amount of time, about 30 to 45 days’ worth of fighting weather left,” Chairman of the Joint Chiefs of Staff Gen. Mark Milley told the BBC. After that, mud and rain would likely have an impact on battlefield maneuverability, he said.

Ukraine though has signaled it is prepared to fight on regardless of the weather.

Kyrylo Budanov, head of military intelligence, acknowledged the counteroffensive was moving more slowly than he would like. Russia’s defensive lines were well-planned, he said, and heavily laid with mines, which made the situation on the battlefield “complicated.”

But even though cold weather was a reality the military cannot ignore, “hostilities will continue, the counteroffensive will continue,” he said.

A looming US election in 2024 has also cast doubt on how much longer Ukraine will receive the support of one of its strongest allies. NATO, and in particular the US, have provided essential military aid to Ukraine to aid its fight against Russia. — CNN