Australia is to become the seventh country in the world to introduce nuclear-powered submarines to its naval fleet, as part of a newly brokered deal between the United States, the United Kingdom and Australia.

The U.S. has said it will sell Australia three U.S. Virginia class nuclear-powered submarines in the early 2030s, with the option to purchase an additional two. The Guardian reports that under the new so-called Aukus partnership, the UK too could see a considerable increase in its deep sea vessels, almost doubling to a reported 19.

Data from the International Institute for Strategic Studies shows that the U.S. has by far the largest nuclear-powered fleet worldwide. Russia has under half the number of nuclear-powered submarines, and China roughly half again. Nuclear-powered submarines do not necessarily mean nuclear-armed but also those fuelled by a nuclear reactor rather than by diesel-electric propulsion.

The plan to bolster Australia’s naval defense comes amidst Western nations’ mounting anxiety over China’s plans for the Indo-Pacific region. Beijing has criticized the move, saying Aukus is encouraging an arms race. China’s foreign ministry spokesperson Wang Wenbin warned in a press conference on Tuesday that the three countries are walking “further and further down the path of error and danger.”