Warren Stephens highlighted how "vital the US-UK relationship is to our countries and to the world" at an event in parliament attended by UK Prime Minister Keir Starmer on Monday.
Stephens said the AUKUS partnership, which is developing a new fleet of nuclear-powered hunter-killer submarines for the UK and Australia, would help maintain a "free and open Indo-Pacific".
The ambassador's decision to make his first public address in support of the project is symbolically important, given it is a legacy of Joe Biden's term in the White House.
The alliance, which also covers collaboration on other advanced technologies, is seen as an attempt to counter the influence of China in the region.
Stephens said AUKUS was based on "peace, security and prosperity".
"Those three ideas lie at the heart of our partnership promoting peace by developing our technologies and deterring our adversaries, bolstering security by training and trading together to fend off threats from cyber attacks to submarines and boosting prosperity by maintaining a free and open Indo-Pacific, while creating jobs and investment from Brisbane to Barrow and to Newport News."
He said AUKUS was a "partnership built on trust, and the United States is proud to stand alongside Britain and Australia, two of our closest allies, as we deepen our collaboration to respond to a changing world".
Stephens also highlighted the economic opportunities from the project.
"Government works best when we get out of the way and let our businesses innovate, compete and collaborate to improve people's lives.
"President Trump and I know this to be true, as it has been repeatedly proven throughout history. That fact is built into the AUKUS partnership, which sees great American, British and Australian companies innovating and investing to maintain our critical technological edge."
Starmer told the event in the House of Lords, organised by the all-party parliamentary group on AUKUS, that "when we talk about security and stability, we mean it - in the Indo-Pacific and here at home".
Australia's high commissioner Stephen Smith told the event: "What underpins economic growth is, of course, security and the AUKUS trilateral partnership is, at its very heart, ensuring we continue to have peace and security, not just in the Indo-Pacific, but in the Euro-Atlantic as well."
17°C