In rare public comments Ukraine's military chief warned on Wednesday of the threat of Russia using nuclear weapons in Ukraine, which would create the risk of a "limited" nuclear conflict with other powers.

The war in Ukraine that began with Russia's invasion on Feb. 24 was likely to rage on into next year, General Valeriy Zaluzhnyi said in an article co-authored by lawmaker Mykhailo Zabrodskyi and published by state news agency Ukrinform.

The article contained by far the Ukrainian commander-in-chief's most detailed assessment of the war to date, and gave starkly contrasting messages to those given by top Ukrainian officials.

"There is a direct threat of the use, under certain circumstances, of tactical nuclear weapons by the Russian Armed forces," Zaluzhnyi said.

"It is also impossible to completely rule out the possibility of the direct involvement of the world's leading countries in a 'limited' nuclear conflict, in which the prospect of World War Three is already directly visible," the article said.

Moscow has in the past denied speculation of potential nuclear or chemical weapons use.

TURNING TIDE

Ukraine will need to match the strike range of Moscow's weapons in order to turn the tide of the war, Zaluzhnyi and Zabrodskyi wrote.

"The only path to a cardinal change in the strategic situation is undoubtedly a series of several consecutive, or ideally simultaneous, counterstrikes by Ukraine's armed forces during the 2023 campaign," they said.

The United States has supplied the Kyiv government with sophisticated long-range weapons on the condition Ukraine would not use them to hit targets inside Russia, according to U.S. officials.

The article contained Ukraine's first acknowledgement that it was responsible for what the authors said were rocket strikes on Russian air bases in annexed Crimea, including one that damaged the Saky military base last month.

Until now, Ukraine refused to publicly acknowledge its involvement, with a senior official speaking on condition of anonymity citing fears of Russian retaliation.

"We are talking about a series of successful rocket strikes against the enemy's Crimean air bases, first of all, the Saky airfield," the article said, using language that did not clarify whether that meant unguided rockets or missiles.

The Saky strike took 10 Russian warplanes "out of action" on Aug. 9, the article said.

Ukraine is not publicly known to have weapon systems in service with a sufficient range to hit Saky, which lies at least 200 kilometres from the front lines.

NO PEACE THIS YEAR

The article's tone contrasted with often optimistic statements by senior Ukrainian officials.

"The length of the war is already measured in months, and there is every reason to believe that this time period will extend beyond 2022," it said.

Zaluzhnyi and Zabrodskyi conceded that Ukraine was positioned "extremely unfavourably" on two eastern frontlines, around the towns of Bakhmut and Izyum.

Foreign-supplied weapons will make up the backbone of Ukraine's defence next year, they said.

"In 2023, the material base of Ukraine's resistance must remain significant volumes of military aid from our partner nations," the article said.