Australia is about to get 220 Tomahawk missiles, which could cost as much as $1.3 billion if the sale goes through.
But what do they do and are they worth the price tag?
What are Tomahawk missiles?
Tomahawks are powerful offensive precision missiles that launch primarily from ships and submarines. They belong to the cruise missile category, which means they fly at subsonic speeds at low altitudes.
They've had many iterations over the years. Each iteration is called a variant, which usually features upgrades or improvements on the original design.
The fourth iteration of Tomahawks, referred to as Block IV, can strike targets 1,600 kilometres away and barrels towards it at Mach 0.74 (913.8 km/h).
Designed for land-attack operations, they're equipped with sophisticated guidance systems that allow a missile to switch targets while in flight.
They can be fired from ships and submarines and can even cruise for hours over a war zone and change course instantly on command.
The Tomahawk missiles are manufactured in America by one of the world's biggest defence contractors, Raytheon Technologies.
How good are Tomahawks?
The US has been the biggest user of Tomahawk missiles since it was first designed by General Dynamics in the 1970s.
According to Raytheon, the US has fired Tomahawk missiles in combat over 2,300 times.
In 2016, the US government bought 149 Tomahawk (Block IV) missiles for US$202.3 million, and in 2017, it purchased another 100 for US$186.9 million.
In 2018, the US Navy launched 66 Tomahawk missiles in Syria. It also relied on it heavily during the Persian Gulf Wars in 1991 in Iraq. They've been reportedly used by the US in Afghanistan, former Yugoslavia, Somalia, Yemen and Libya.
Block V was introduced in 2021 and is the latest variant of the Tomahawks. It's more advanced, can hit moving targets at sea and can hit more diverse land targets.
It's unclear which variant of the Tomahawks the Royal Australian Navy will get.
How do they stack up against Chinese missiles?
China has a wide variety of missiles, including intercontinental ballistic missiles known as ICBMs. The DF-31, DF-41 and DF-5 can hit targets from 7,000 to 15,000 kilometres away.
They can also carry nuclear warheads. Australia doesn't have ICBM capability.
But their more comparable DF-21 missiles are medium-range ballistic missiles known as MRBMs. With superior range to the Tomahawks, they can hit targets up to 2,150 kilometres away. They can also carry nuclear warheads.
In addition, the Chinese military possesses the HN-1, HN-2 and HN-3 cruise missiles that can hit targets from 600 to 3,000 kilometres away.
Those also can carry nuclear warheads and can be fired from the ground, ships, submarines and the air.
It also has its anti-ship YJ-18 missile and its variants which can be fired from ships, submarines and the ground. It has a cruising speed of Mach 0.8 and can hit targets up to 540 kilometres.
What missiles have we got now?
The Australian Navy has a variety of missiles in its arsenal. Each is better suited to a specific job, both offensive and defensive.
1. Hellfire
These precision air-to-ground missiles can hit targets 8km away and travel at Mach 1.3 or 1,600 km/h. They're the preferred armament for the MH-60R Seahawk helicopters, which can carry up to eight at a time.
They are manufactured by the American defence juggernaut Lockheed Martin.
2. Harpoon Block II
The Harpoon is a high-speed anti-ship missile with a range of up to 124 km.
Manufactured by Boeing, a Harpoon missile uses GPS-aided inertial navigation to strike targets on land and in the water.
They're often used on Anzac Class Frigate Helicopter ships, like the HMAS Warramunga.
3. Evolved Sea Sparrow Missile
Also used on Anzac Class frigates, the Sea Sparrow is a defensive surface-to-air missile. They are designed to be an anti-anti-ship missile.
They fire from vertical silos on board destroyers like the new Hobart Class ships at Mach 4, four times the speed of sound.
They are manufactured by Raytheon, the same company responsible for the Tomahawks.
4. SM-2 Standard Missile
According to the Australian Navy, this surface-to-air missile has been described as "the world's premier surface-to-air defence weapon".
Like the Sea Sparrow, it's also used for defence against anti-ship missiles and enemy aircraft. It can hit speeds up to Mach 3 and is also manufactured by Raytheon.
