A US Defense Department official says the United States will deliver Abrams battle tanks to Ukraine as early as this fall, so Kyiv will be able to defend itself against Moscow's invasion.

The Biden administration announced in January that it would send 31 advanced M1A2 Abrams tanks to Ukraine, but it did not provide a concrete delivery schedule.

Pentagon spokesperson Brigadier General Patrick Ryder spoke with reporters on Tuesday. He said the US has decided to provide refurbished model M1A1 tanks, which it has in stock, because it would probably have taken over a year to deliver the M1A2 tanks as planned. The M1A1 is the older version of the M1A2.

Ryder said the decision will "significantly expedite delivery timelines." He also said that it will enable the US to "deliver this important capability to Ukraine by the fall of this year."

He added that Ukrainians were trained to use the ground-to-air Patriot missile system faster than expected. He said the US is confident that it will be able to get the Patriot systems to Ukraine earlier than planned.