THE HAGUE, Nov 14 (AFP) - It is up to Ukraine to decide what terms are acceptable for negotiations to bring an end to the war Russia is waging against the country, NATO Secretary General Jens Stoltenberg said on Monday, warning Moscow's strength should not be underestimated despite Kyiv's recent battlefield successes.

Earlier on Monday, Ukrainian President Volodymyr Zelenskiy visited the newly recaptured southern city of Kherson in what marked Russian President Vladimir Putin's third major setback since the start of the war in February.

"We should not make the mistake of underestimating Russia. The Russian armed forces retain significant capabilities, as well as a large number of troops," Stoltenberg said during a joint news conference with Dutch government officials in The Hague.

"The coming months will be difficult. Putin's aim is to leave Ukraine cold and dark this winter. So we must stay the course," he said.

Echoing U.S. Secretary of State Antony Blinken's comments over the weekend, Stoltenberg said it was up to Ukraine to decide when and how it wanted to negotiate with Russia to end the war.

"They are paying now the highest price in terms of lost lives and damage to the country. So it is for Ukraine to decide what kind of terms are acceptable for them," he said.

"What happens around the table is fundamentally linked to the situation on the battlefield," Stoltenberg said. "So what we should do is to support Ukraine and to strengthen their hand so that at some stage there can be negotiations where Ukraine prevails as an independent sovereign nation in Europe," he added.