Pentagon chief Lloyd Austin has met with Germany's new Defense Minister Boris Pistorius to pressure Berlin to authorize the transfer of German-made tanks to Ukraine, U.S. officials said, as the two allies remain at odds over the issue.

Germany will allow German-made tanks to be sent to Ukraine for defense against Russia if the United States agrees to send its own tanks, a German government source told Reuters.

But U.S. officials have insisted publicly and privately that Washington has no plans yet to send American-made tanks to Ukraine, arguing that it would be too difficult for Kyiv to maintain them and would require a huge logistical effort just to get them up and running.

Before the talks began, Austin thanked Germany for its support of Ukraine. Germany remains one of our most important allies ... I would like to thank the German government for everything it has done to strengthen Ukraine's self-defense, Austin said, without specifically mentioning the issue of tanks.

A senior U.S. Defense Department official believes that supplying Ukraine with German-made Leopard tanks makes the most sense because a number of countries already have them and are ready to hand them over quickly.

A second U.S. official said that the administration of President Joe Biden must approve a new aid package to Ukraine worth more than $2 billion.

The package, which could be announced as early as Friday, will likely include Stryker armored vehicles, but not M1 Abrams tanks.