"Our support for the forces of freedom in Ukraine holds strong and true," Austin told a meeting of dozens of Kyiv's supporters at the Ramstein air base in Germany.

The meeting of the Ukraine Defence Contact Group "will focus on three key issues: air defense, ammunition, and enablers," he said, referring to logistics and other support that allows military units to operate.

Contact group members have provided more than $55 billion in security assistance to Ukraine and over $35 billion of this has come from the United States, Austin said.

"We reject (Russian President Vladimir) Putin's grim vision of a world where tyrants get to assault their peaceful neighbours, he said, adding: "Together, we will make sure that Ukraine has what it needs to live in freedom."