The United Kingdom, the United States, and Australia have announced a special security agreement to share high-level defense technology to counter China.
The partnership will enable Australia to build nuclear submarines for the first time.
The treaty, to be known as Aukus, will also address counterfeit espionage, atomic technologies, and communication system science.
The three countries are concerned about China's growing power and military presence in the India-Pacific region.
As a result of the agreement, Australia has scrapped a plan to build submarines designed by France.
France won a $ 50 billion contract to build 12 submarines for the Australian Navy in 2016. The agreement was Australia's largest defense agreement.
However, the project was delayed because of Canberra's demand that most of the equipment comes from within.
On Wednesday, US President Joe Biden, British Prime Minister Boris Johnson, and his Australian counterpart Scott Morrison issued a joint statement on the launch of a new security partnership, called Aukus.
"As a first initiative under the Aukus ... we are committed to jointly supporting Australia in acquiring nuclear-powered submarines for the Australian Navy," the statement said.
"This capacity will promote stability in the India-Pacific region and will be used to support our values and common interests," it said.
The leaders said the goal was to "bring Australia's potential into early service delivery", adding: "Australia remains committed to fulfilling all its responsibilities as a nuclear-free state."
It went on to say that the protection agreement would also take into account the capabilities of the network, artificial intelligence, and "additional underwater capabilities".
BBC's Jonathan Beale's analysis
The British government says this is a very important protection agreement - an argument reinforced by the fact that British, American, and Australian leaders have appeared together in a video conference to announce this partnership. It also emphasizes the growing importance of the India-Pacific region for the United States and the United Kingdom.
It will be beneficial to the other two countries. First, France, a Nato ally, had signed an agreement to build a submarine for the Australian Navy. The plan is now dead.
The second is China. Although British officials insist the new security agreement is not the answer for any country, the British government says it is about ensuring prosperity, security, and stability in the region and supporting "peace". And it is no secret that Britain, the United States, and Australia are concerned about the Chinese military building in the India-Pacific region.
Mr. Johnson said the three nations were natural allies and that the alliance would "bring us closer than ever before".
"This partnership will continue to be important in defending our interests, and ... protecting our people at home," he said.
In recent weeks, the Queen Elizabeth British HMS Ship was sent to the India-Pacific region along with personnel and equipment from the United States.
The joint statement said India-Pacific had unresolved regional conflicts, terrorist threats, and the problem of organized crime. "It's an area facing new security challenges, as well as the internet," it said.
