Ukraine has not used US-made Abrams tanks since they arrived in September, analysts said.
Ukrainian forces are likely keeping them in reserve for next spring, they told Business Insider.
Winter, Russia's fortified defensive lines, and logistics have made tanks obsolete, they said.
The US sent 31 advanced M1A2 Abrams tanks to Ukraine in September — but they've been notably absent from an actual fighting there.
Analysts told Business Insider that this is probably because it's hard to put them to good use, citing the worsening weather and Russia's hardcore defensive lines.
The tanks are unlikely to make an appearance until spring, they concluded.
"Since the front is stable, the Ukrainians are likely keeping them in reserve," said Mark Cancian, a retired US Marine Corps colonel who is now a senior advisor with the Center for Strategic and International Studies.
Since receiving its first batch of Abrams in September, Ukraine has likely mixed them with the US-made M2 Bradley infantry fighting vehicles, Cancian told BI.
Bradleys arrived sooner and have made their presence felt on the battlefield already.
For now, because of winter conditions, sending small Bradley-and-Abrams groups would be "inefficient" and "hard to support" logistically, he said.
Winter in Ukraine means mud, rain, frost, and snow that can be hellish to drive through. The conditions prevented any major breakthroughs last winter, Business Insider's Sinéad Baker previously reported.
Ukrainian forces would be "waiting for the right moment," probably spring, when a new offensive could be launched, Cancian said.
Kateryna Stepanenko, a Russia expert at the Institute for the Study of War, said that her colleagues have seen no evidence that Abrams have been committed to battle so far.
She made a similar assessment to Cancian, telling BI that rain and mud were preventing the use of heavy military equipment.
Sergej Sumlenny, founder of the European Resilience Initiative Center in Germany, said the US missed its moment to send its Abrams tanks.
The delay in Ukraine's allies sending advanced tanks gave Russian troops enough time to build heavily-fortified defensive lines, he noted.
Russia's miles of trenches, rows of concrete "dragon's teeth," and minefields mean Western tanks have little chance to shine on the battlefield, he told BI.
Sumlenny cited the July offensives by the 47th Mechanized Brigade in the Zaporizhzhia region, where he said Ukrainian troops suffered heavy losses of Bradley armored vehicles against Russian defenses.
At the time, 34 of the 100 Bradley tanks the US had provided had been destroyed, according to Oryx, an open-source military research group.
"That was the only instance where the Ukrainians used the Western tanks in a frontal assault," Sumlenny said. They did not seem willing to try that again.
Now, with Russia's defensive lines stretching over 1,000 kilometers, or 745 miles, he said the 31 US-provided Abrams tanks are too few to play a "decisive" role in the war.
"That's just three tanks per one hundred kilometers — that's ridiculous," he said.
Ukraine's Ministry of Defense didn't immediately respond to Business Insider's request for comment.
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