The plan to provide Australia with nuclear-powered attack submarines and support to Ukraine's military are on the agenda at a meeting between US Secretary Of Defence Lloyd Austin and his British counterpart Ben Wallace.

During remarks before their meeting at the Pentagon, Austin said the AUKUS alliance showed the countries commitment "to a free and open Indo-Pacific".

"It is an historic opportunity that shows how strong we can become when we work together," Austin said.

"It shows our deep commitment to a free and open Indo-Pacific and it's a testament to our shared values and to the long term investments that we're making in our forces.”

Wallace praised the long term commitment of the alliance and even joked that the plan would yield results so far in the future that neither him nor Austin would be holding the office by the time the first AUKUS submarine is delivered.

“Our long term friendship is also a long term partnership and AUKUS is that symbol," Wallace told Austin.

"While, I might make it to four years and you might make it to five or six (holding the office) I suspect we won't be sitting here when the first AUKUS submarine rolls off the production line. It would be a remarkable feat of political survivability to do so.

"But it shows that is a long term commitment of some of our greatest secrets and our greatest capabilities.”

The United States, Australia and Britain plan to provide nuclear-powered attack submarines is expected to come into force by the early 2030s to counter China's ambitions in the Indo-Pacific.

Austin also praised the UK for its role in supporting Ukraine in the war against Russia, describing Britain as "a leader in providing urgently needed assistance and training to Ukrainian forces".

"And, beyond your contributions, the UK is working with allies and partners to encourage donations and facilitate the delivery of security assistance to Ukraine," Austin said.

"I look forward to a great discussion, including finding ways to continue to work together to help Ukraine and to further strengthen our partnership.”

Wallace returned the praise, commending the US on its global leadership.

“Since this time with the invasion of Ukraine, we've seen a more anxious world and a more unstable world and without US leadership, we would be in a worse place," he said.

"Whether that is in the Pacific, whether that is in Ukraine, whether that is in European defence, or indeed worrying so the developments in the Middle East, Iran and Iraq.”