The US will send the M1A2 Abrams tank to Ukraine, which has significantly upgraded capabilities compared to the earlier M1A1 model.

Deputy Pentagon press secretary Sabrina Singh confirmed Thursday that the M1A2 would be the version of the Abrams provided to the Ukrainians. She said that the US does not “have these tanks available in excess in our US stocks,” and it will take “months to transfer” the tanks to Ukraine.

The M1A2 is a significant upgrade from the older M1A1, mostly due to the fact that the A2 runs on a digital system, as opposed to the analogue system of the A1.

It’s “the difference between a plug-in phone – a rotary phone – and that iPhone you’ve got in your hand,” explained retired Army Gen. Robert Abrams, the former commander of US Forces Korea, whose father was the namesake for the 70-ton tank.

US officials announced this week that 31 Abrams tanks would be sent to Ukraine after days of back and forth between the US and its allies. Officials had not yet disclosed which tank variant they would choose, and Army acquisitions chief Doug Bush told reporters on Tuesday that the decision was still being deliberated.