Pentagon spokesman John Kirby said defense ministers and senior generals of 20 countries, NATO and non-NATO members, have already accepted the invitation from US Defense Secretary Lloyd Austin for the meeting Tuesday at the US-controlled Ramstein Air Base in western Germany.

He called the meeting a consultation that would examine how Ukraine's partners can contribute to shoring up its military strength after the war ends.

"One of the things that the secretary wants to come out of Tuesday in Ramstein is the beginning of a discussion with like-minded nations about long-term defense relationships that Ukraine will need going forward," Kirby told reporters.

"It's really largely about modernizing and making sure their military is still potent and capable going forward. It's not about security guarantees, it's about their actual military posture," he said.

The meeting comes two months into the war, as Ukraine forces push back against a new Russian offensive in south and east Ukraine. Russian forces were driven out of northern Ukraine in a major setback for the initial invasion.

The United States has led about 30 countries in supplying military equipment, munitions and other supplies to Ukraine forces to sustain the fight.

Kirby said Austin and those attending will discuss how they can continue to help with Ukraine's current needs and what arms various partners can supply as the war develops.

"But I think he also wants to take a longer, larger view of the defense relationships that Ukraine will need to have going forward when the war is over."

That includes cataloguing the industrial potential of partners to see how their arms manufacturers can continue to help Ukraine, he said.

Kirby stressed that the meeting was not under NATO's auspices, and would not necessarily produce any immediate concrete results.