The official spoke on the condition of anonymity to provide an update on US weapons support for Ukraine before Friday’s Ukraine Defence Contact Group meeting.

The tanks have been moved from the front lines, and the US will work with the Ukrainians to reset tactics, said Joint Chiefs of Staff Vice Chairman Adm. Christopher Grady and a third defence official who confirmed the move on the condition of anonymity.

“When you think about the way the fight has evolved, massed armour in an environment where unmanned aerial systems are ubiquitous can be at risk,” Grady told the AP in an interview this week, adding that tanks are still important.

“Now, there is a way to do it,” he said. “We’ll work with our Ukrainian partners, and other partners on the ground, to help them think through how they might use that, in that kind of changed environment now, where everything is seen immediately.”

News of the sidelined tanks comes as the US marks the two-year anniversary of the Ukraine Defence Contact Group, a coalition of about 50 countries that assesses Kyiv’s battlefield needs and identifies where to find needed ammunition, weapons or maintenance to keep Ukraine’s troops equipped.

Recent aid packages, including the $1 billion military assistance package signed by President Joe Biden on Wednesday, also reflect a wider reset for Ukrainian forces in the evolving fight.

They also taught the Ukrainians how to use them in combined arms warfare — where the tanks operate as part of a system of advancing armored forces, coordinating movements with overhead offensive fires, infantry troops and air assets.

As the spring progressed and Ukraine‘s highly anticipated counteroffensive stalled, shifting from tank training in Germany to getting Abrams on the battlefield was seen as an imperative to breach fortified Russian lines.

Ukrainian President Volodymyr Zelensky announced on his Telegram channel in September that the Abrams had arrived in Ukraine.

Since then, however, Ukraine has only employed them in a limited fashion and has not made combined arms warfare part of its operations, the defence official said.

During its recent withdrawal from Avdiivka, a city in eastern Ukraine that was the focus of intense fighting for months, several tanks were lost to Russian attacks, the official said.

A long delay by Congress in passing new funding for Ukraine meant its forces had to ration ammunition, and in some cases they were only able to shoot back once for every five or more times they were targeted by Russian forces.