“These will be excess hulls in our inventory that we will refurbish, refit” by drawing from existing stocks and Ukraine security assistance “in order to make them combat-ready”, Brigadier General Pat Ryder told reporters, declining to specify where the work would occur.

The move underscores the urgency the US and its allies feel in their support of Ukraine in the face of Russia’s sustained missile and artillery barrages.

National Security Council spokesperson John Kirby told MSNBC earlier Tuesday that the Pentagon would have more to say soon about a revised timetable “to see if we can get Abrams tanks to Ukraine a little bit faster than previously expected”.

“There’s some some changes that you can make to the process to sort of speed that up,” Kirby said.

The US will take the hulls of 31 older tanks from its inventory and pay contractor General Dynamics to refurbish them into the M1A1 SA model of the Abrams, not the newer M1A2, according to two US defence officials who asked not to be identified in advance of an announcement.

In January, the Pentagon allocated $400-million in Ukraine Security Assistance Initiative funding for the tanks, and Ryder said Tuesday that he didn’t expect the revised plan to add significant costs.

After initially refusing to do so, the US announced in January it would send Ukraine 31 of its M1 Abrams battle tanks. The move was made to encourage Germany to supply some of its Leopard tanks even sooner to give Ukraine a major new capability as it tries to pry Russian forces from the east.

Those tanks are available in larger quantities, are closer to the front lines and are easier to operate and maintain.

The Abrams tanks won’t be in Ukraine in time for expected spring offensives by Russia and Ukraine, but the less complex German-built tanks are already arriving from Poland.

Kirby pointed to the sophistication and limited availability of the Abrams and the associated training and logistics requirements as reasons for the long lead time for delivery to Ukraine.

“Just for instance, the basic training on the Abrams tanks for American soldiers is 16 weeks long, and that’s just the basic training on how to operate it,” he said on MSNBC. “Then you have to know how to maintain it. And then you have to have a supply chain setup to actually keep the parts and supplies going, while you’re in combat, while you’re fighting, and while these tanks are no doubt going to be taking some hits.”