The purchase agreement for Virginia-class submarines will be announced Monday when President Joe Biden, Australian Prime Minister Anthony Albanese and U.K. Prime Minister Rishi Sunak meet in San Diego for talks on the 18-month-old nuclear partnership known by the acronym AUKUS. The people spoke on the condition of anonymity to discuss the matter ahead of the announcement.

The AUKUS agreement, announced in 2021, paved the way for Australia to get access to nuclear-powered submarines, which are stealthier and more capable than conventionally powered boats.

“We all recognize the imperative of ensuring peace and stability in the Indo-Pacific over the long term,” Biden said in September 2021 when the partnership was announced. “We need to be able to address both the current strategic environment in the region and how it may evolve.”

The secretly brokered deal included the Australian government’s cancellation of a $66 billion contract for a French-built fleet of conventional submarines, which sparked a diplomatic row within the Western alliance that took months to mend.

The European official said France had been briefed on the terms of the purchase agreement. Biden spoke with French President Emmanuel Macron on Tuesday, the White House said, adding that they “discussed the cooperation between the United States and France in the Indo-Pacific region.”

The submarines, which cost $3 billion each, are built at shipbuilding plants in Virginia and Connecticut. Under the terms of the agreement, subs would eventually also be built in the U.K. and in Australia with U.S. technology and support, the person familiar with the matter said. The initial plans called for all of the subs to be constructed in Adelaide, Australia.

The U.S. would also step up its port visits in Australia to provide the country with more familiarity with the nuclear-powered technology.

While relations between the U.S. and France have recovered over the submarine deal, the French continue to convey concerns that the deal could potentially be used by China as an excuse to stretch the boundaries of the Nuclear Non-Proliferation Treaty and deliver sensitive technologies to adversaries of the West, according to the European official. The official added that France has urged the three AUKUS alliance members to be mindful of the issue as they proceed.

China has argued that the AUKUS deal is in violation of the treaty, arguing that transfer of nuclear weapons materials from a nuclear-weapon state to a non-nuclear-weapon state is “blatant” violation of the spirit of the pact. Australian officials have pushed back against the criticism, arguing that it is looking to acquire nuclear-power and not nuclear-armed submarines.

The White House declined to comment on the submarine purchase ahead of the planned meeting on Monday.