WASHINGTON — Putting aside resistance from the Pentagon and elsewhere, the Biden administration is planning to announce a decision to send Abrams M1 tanks to Ukraine, officials said Tuesday.

The tanks, long sought by Ukrainian President Volodymyr Zelenskyy, would provide the heaviest weaponry yet among the billions of dollars in military aid Washington has sent to Ukraine to help repel a brutal Russian invasion.

But given the sophistication, complexity and firepower of the tanks, it could be months or even more than a year before they reach the battlefield and Ukrainian fighters are trained to use the equipment.

Pentagon spokesman Brig. Gen. Pat Ryder, in a nod to objections from Defense Department officials, said the Abrams tank was a major asset in combat, but not one that is easy to operate.

The tank “is a very capable battlefield platform,” he said Tuesday.

“It’s also very complex capability,” he added. “And so, like anything that we’re providing to Ukraine, we want to ensure that they have the ability to maintain it, sustain it, to train on it.”

He emphasized he was not announcing a decision to supply the tanks “at this time,” an official position repeated at the White House and State Department.

But U.S. officials are also keen to send a political message to Germany, which has been reluctant to provide its own Leopard tanks to Ukraine unless the U.S. also offers tanks.

Germany may be softening its position, born of decades of an official post-World War II position of pacifism. And Poland, for example, has Leopard tanks it would like to ship to Ukraine, but has sought permission from Germany to do so.

In recent days, however, Poland has suggested it would send the tanks with or without German authorization. Germany has signaled it would no longer object.

The Leopard pales in comparison to the Abrams, U.S. officials say, but would be easier to operate initially on European terrain, where it has long-term experience.