In late 2017 the U.S. Navy ordered another 196 Tomahawk Block 4 Land-Attack missiles for use from VLS (Vertical Launch System) cells. These will cost about $1.1 million each. Most Tomahawks in U.S. service are fired from surface ship or nuclear submarine (SSN) VLS cells. There is also a version for use from torpedo tubes, which is all British SSNs use. The Tomahawk has quietly become the primary offensive weapon for the American fleet.
The RGM-109E Block 4 Tomahawk Land Attack Missile weighs 1.2 ton, is six meters (18 feet) long, has a range of 1,600 kilometers. It reaches its target at a speed of 600-900 kilometers an hour, flying at an altitude of 17-32 meters (50-100 feet), and propelled by a jet engine generating only 273 kg (600 pounds) of thrust. Accuracy is on a par with JDAM (10 meters/ 31 feet). The Block IV Tomahawk can be reprogrammed in flight to hit another target and carries a vidcam to allow someone to check on prospective targets.
There’s also the new JMEW (Joint Multi-Effects Warhead System) warhead for the Tomahawk. This is a 450 kg (1,000 pound) warhead designed mainly for penetrating underground bunkers, but it will also provide excellent blast effect for less robust targets. Exact penetration was not revealed. JMEW uses laser terminal guidance, enabling it to hit within a few meters (ten feet) of its aiming point. JMEW can also hit moving targets, like ships.
The Tomahawk, when it showed up in 1983, was one of the first combat UAVs but it wasn't reusable. The Tomahawk has been a primary land attack weapon for surface ships and submarines since the 1990s. Over 6,000 have been manufactured so far. The U.S. Navy has fired over 2,200 in combat and over 600 for training and testing. The U.S. Navy currently has over 3,000 Tomahawks on its warships or in storage. Tomahawk is expected to remain in service until 2040, with older ones refurbished (batteries and electronics replaced or upgraded, same with elderly mechanical components) to extend their useful lives.
The Block 3 entered service in 1994, but the 2012 Block 4 was a big upgrade with the addition of GPS and remote control in flight. The more recent upgrades added improvements in the guidance system and defensive capabilities against electronic jamming. The need for these new features was seen in 2015 when the navy tested the current Block 4 Tomahawk to see if its new two way communications capability could enable it to effectively hit moving targets. The Block 4 managed to do so, but not under combat conditions. That is, not with warships using defensive or electronic weapons to shoot down the incoming missile or mislead its guidance system. One navy test used a nearby aircraft (which could be a UAV) that was tracking the exact location of the target ship. That could also be done from a space satellite. Thus a fully developed anti-ship capability for Tomahawk will require regular upgrades in the guidance system to make it capable of operating without constant two-way communications.
The navy is aware of the fact that Tomahawk is not the ideal anti-ship missile. Against modern defenses anti-ship missiles have to move faster than a Tomahawk and be equipped with a better terminal guidance system. The speed problem cannot be fixed, but the Tomahawk could be equipped with a more capable terminal guidance system. That might be able to handle the tracking and targeting systems for gun and missile systems designed to knock down anti-ship missiles when they get close. In any event, Tomahawk Block 4 has a way to go before it is a competitive anti-ship missiles against modern warships. But developing and testing upgrades will give Tomahawk a useful anti-ship capability, just not make it the most effective anti-ship missile out there.
There are apparently some novel concepts for using a radically new anti-ship warhead that turns Tomahawk into a two stage missile with the warhead making the final attack at much higher speed. That may not work but because Tomahawk is a stable and reliable design with lots of combat experience it is easier to tinker with the guidance system, warhead and range and come up with affordable new capabilities that work. That works because one reason for the continued usefulness of Tomahawk is its ability to do more and more things reliably.
Because of these constant improvements and consistent reliability American (and other) warships continue to use Tomahawks in combat on a regular bases. The targets tend to be on land and not mobile. Most of these uses are publicized, but some are not. Several hundred Tomahawks were used against Libya in 2011 and that demonstrated the effectiveness of Tomahawks in delivering major airstrikes on short notice, anywhere in the world without losing more expensive manned aircraft and exposing their pilots to getting shot down and captured.
The Tomahawk replacement will be the NGLAW (Next Generation Land Attack Weapon). Development of a successor to the Tomahawk has been underway since the 1990s and the current (NGLAW) concept is for a cruise missile that will be heavier (2.2 tons), have a longer range (2,000 kilometers), and a larger (one ton) warhead than the Tomahawk. The NGLAW will be stealthier and use a combination of new guidance and targeting systems to improve the chances of success. Price will probably be the key factor but it is expected to cost at least twice as much as the current Tomahawk.