(CNN)-- President Joe Biden on Wednesday unveiled a new effort to help Australia acquire nuclear-powered submarines, a major step toward countering China as he works to build international backing for his approach to Beijing.

The announcement came as part of a new trilateral partnership among the United States, Australia and the United Kingdom that the three countries' leaders jointly revealed Wednesday afternoon.

"The United States, Australia and the United Kingdom have long been faithful and capable partners and we're even closer today," the President said. "Today, we're taking another historic step to deepen and formalize cooperation among all three of our nations, because we all recognize the imperative of ensuring peace and stability in the Indo-Pacific over the long term."

The partnership kicks off what is expected to be a flurry of diplomatic engagements for Biden this autumn, from next week's United Nations meetings to a White House summit of Asian leaders to October's Group of 20 talks in Italy.