Australia is buying five nuclear-powered submarines from the United States. The deal was announced Monday, Mar. 13 in San Diego.

The five submarines will be Virginia-class boats. Designed by General Dynamics Electric Boat and Huntington Ingalls Industries, Virginia-class submarines can complete a broad spectrum of missions including anti-submarine warfare and intelligence, surveillance and reconnaissance (ISR) missions.

The five submarines will cost Australia about $3 billion per submarine, at least using current market prices. The ships will be built at plants in Virginia and Connecticut.

The deal is part of the wider AUKUS agreement between Australia, the UK and the U.S. AUKUS was announced in 2021, and paved the way for Australia to access nuclear-powered submarines. The secretly brokered deal included the Australian government’s cancellation of a $66 billion contract for a French-built fleet of conventional submarines. The cancellation of the French deal created a diplomatic wedge between the U.S. and France which took months to mend.

Nuclear subs are stealthier and more capable than their conventional counterparts. Under the AUKUS agreement, nuclear-powered subs will eventually be built in Australia and the UK as well, with technology and support coming from the United States.

Like the United States, both Australia and the UK see China as the greatest threat to military and economic stability in the Pacific. Rishi Sunak, the British Prime Minister, said China represents an “epoch-defining systemic challenge” to the UK and its allies. To try and overcome that challenge, Sunak said he’s authorizing an additional $6 billion in military spending, the bulk of which will bolster Britain’s nuclear program, including enhancing its nuclear submarine fleet.

Beijing called the AUKUS deal a violation of the Nuclear Non-Proliferation Treaty, because nuclear materials are being transferred to a non-nuclear-weapon state. The Australian government said AUKUS doesn’t violate any non-proliferation agreements because Australia is buying nuclear-powered submarines, not nuclear-armed submarines.

The Associated Press contributed to this report.