The submarines and nuclear missiles are not designed for protection but for aggression, the pacifist organization pointed out via Twitter.
Stop the War, known for its anti-war campaigns, also stressed that the trilateral agreement made it clear that the global United Kingdom that Prime Minister Boris Johnson is advocating for after Brexit will bring with it more militarism and confrontation.
Johnson, Australian Prime Minister Scott Morrison and US President Joe Biden announced the formation of an alliance in the Asia-Pacific region that is seen by most analysts as a formula to counter the influence of China in the region.
The pact known as AUKUS includes the acquisition by Australia of a fleet of nuclear submarines built using US technology and British workforce.
It also includes the development of artificial intelligence and quantum and cybernetic technologies for military use.
The new alliance not only provoked an angry reaction from China, which saw it as a threat to regional peace and stability and a pretext to intensify the arms race, but also upset France, a member of the North Atlantic Treaty Organization and ally of the three powers.