The first group of about 400 Ukrainian soldiers has started training in Germany on how to operate and maintain American M1 Abrams tanks, according to the Pentagon, another significant step in arming Kyiv as it seeks to reclaim territory from Russia.

About 200 of the troops — roughly one armored battalion — on Friday began conducting what the military calls combined arms instruction at training ranges in Grafenwoehr and Hohenfels, Germany, Lt. Col. Garron Garn, a Pentagon spokesman, said in a statement.

That instruction includes basic soldiering tasks like marksmanship and medical skills, along with training at platoon and company levels, and eventually larger exercises involving battalion-size units facing off against each other.

The other 200 Ukrainian soldiers began training on how to fuel and maintain the tanks, Colonel Garn said.

Defense Department officials had previously said that about 31 tanks would be sent to Germany to be used in a training program for Ukrainian troops that is expected to take 10 to 12 weeks. Combat-ready tanks could reach the battlefields in Ukraine by the fall, the officials have said.

Pentagon officials had expressed misgivings about sending the Abrams, citing concerns about how Ukraine would maintain the advanced tanks, which require extensive training and servicing. And officials had said it could take years for them to actually reach Ukrainian battlefields. But Defense Secretary Lloyd J. Austin III eventually came around to the view that committing to sending American tanks was necessary to spur Germany to follow with its coveted Leopard 2 tanks.

Initially, American defense officials had said that the M1 Abrams tanks would not arrive in Ukraine until next year. But since January, when the Biden administration reversed its longstanding resistance and announced that it would send the tanks, senior defense officials have said that they wanted to speed up the timeline.

The start of the tank instruction, led by the 7th Army Training Command, comes a week after President Biden told U.S. allies that he would allow Ukrainian pilots to be trained on American-made F-16 fighter jets, a step toward eventually letting other countries give their American-made planes to Ukraine.

Ukraine is preparing a major counteroffensive, hoping to retake more territory seized by Russia in the war’s early days. As with the fighter jets, the delivery of Abrams tanks and trained crews would be months away, too late to affect that plan.