The US and UK both use nuclear tipped Trident ballistic missiles on their "boomers" and the "attack" subs protect the boomers and have Tomahawk missiles.
The UK and US boomers carry Trident ballistic missiles armed with multiple nuclear warheads. Their mission, essentially, is to stay at sea for months at a time, the vast majority of it submerged, and be prepared to launch a retaliatory nuclear strike should an adversary launch one of their own against the UK or US.
Each of the US ballistic missile subs can carry 20 Trident missiles (16 for the UK subs) with as many as eight warheads (three for the UK subs) per missile. They are able to be shot over a range of 4,600 miles (7,400 kilometers). The nuclear warheads have blast yields between 100 kilotons and 475 kilotons. By contrast, the atomic bomb dropped on Hiroshima, Japan, during World War II had a yield of 15 kilotons.
The US has 14 ballistic missiles subs, while Britain has four. These are not the submarines Australia is signing on for.
The US has three classes of attack subs in its fleet of 53. The newest of these are the 19 of what's called Virginia class.
Armed with dozens of Tomahawk cruise missiles and torpedoes, the 377-foot, 8,000-ton Virginia-class subs can cruise at more than 28 mph (46 kph) and stay submerged indefinitely. Their time underwater is limited only by the need to resupply provisions for the crew of 132.
The UK's four Astute-class attack subs are even faster than the US subs, capable of more than 35 mph (56 kph) submerged, and like the US carry the Tomahawk cruise missile.
t takes a long time -- possibly decades -- to develop a nuclear-powered submarine and get it deployed. The three-party deal announced Wednesday only provides for an 18-month study to see how to best build nuclear-powered subs for Australia.
Australian Prime Minister Scott Morrison said it could be 2040 before the new subs are in the Australian fleet.
https://www.cnn.com/2021/09/17/australi ... index.html
"Tomahawk IV is the latest version of the missile. It has a longer range than its predecessors (well in excess of 1,000 miles), can be directed at a new target in mid-flight, and can also beam back images of the battlefield to its mother submarine," the Royal Navy's website says.
That's the kind of firepower and endurance Australia wants as it looks to protect its northern waters from any naval threats and project its naval power into the South China Sea, where it, along with the United States, looks to blunt Chinese influence and protect freedom of navigation.
I'd assume that this project will be fast tracked.
"Everyone is entitled to their own opinion, but not their own facts." - Daniel Patrick Moynihan