What Are ‘Artillery Rockets,’ and Why Is the U.S. Sending Them to Ukraine?

As the fighting in eastern Ukraine turns into an artillery duel, the Pentagon announced that it would send its most advanced artillery rocket launcher and munitions to the Ukrainian military in the hope of giving it an edge over Russia.

Here’s how the system works, and what it could potentially do, as the war stretches into a fourth month.

What is an artillery rocket?

An artillery rocket is a weapon that is typically propelled by a solid-fuel motor and can carry a variety of warheads. During the Cold War, most artillery rockets were unguided and imprecise when fired at greater distances.

In the 1970s, the United States invested in a new weapon it called MLRS, for Multiple Launch Rocket System, designed for use in the event that Russian armored vehicles massed for World War III on the border of Western Europe.

The M270 MLRS launcher was an armored vehicle that could carry two “pods” of munitions. Each pod held either six cluster-weapon rockets that could fly about 20 miles, or a single, larger guided missile, called ATACMS, for Army Tactical Missile System, that could fly about 100.

The 23-ton launcher moved on treads, at speeds up to 40 miles per hour.

Years later, the Pentagon introduced a more easily transportable version called HIMARS, for High Mobility Artillery Rocket System, which is based on a wheeled truck that is much lighter. Unlike its predecessor, the M142 HIMARS truck carries only one pod of munitions, but it can move much faster both on and off-road, and can be shipped on a C-130 cargo plane.

Has the United States used these weapons?

Yes. During Operation Desert Storm, government records show that the U.S. Army fired more than 17,200 unguided MLRS rockets and 32 of the larger ATACMS guided missiles at Iraqi forces. The submunitions carried by those rockets had a high failure rate, and the duds left behind killed and wounded many U.S. troops.

In 2005, the Army fired a new guided rocket, known as a GMLRS, in combat in Iraq for the first time. That rocket has a range of more than 40 miles, more than twice that of the older rockets, and its navigation is aided by GPS signals.

Since the invasion, the Pentagon has provided Ukraine with 108 M777 howitzers, the most lethal weapons the West has delivered so far. But the range of the GMLRS is more than twice that of the 155-mm shells fired by howitzers.

The Pentagon has spent approximately $5.4 billion to buy more than 42,000 of the GMLRS since 1998, according to a report published by the Congressional Research Service last year, and commanders in Iraq and Afghanistan used them frequently.

What’s the difference between a rocket and a missile in this context?

The nomenclature can be confusing sometimes, but generally the word “rocket” is used in a military context to refer to relatively inexpensive unguided weapons powered by solid-fuel motors, while “missile” is generally shorthand for “guided missiles,” more expensive and complicated weapons that use movable fins to steer themselves to their targets and can fly much farther.

The Pentagon has already sent short-range, inexpensive and unguided antitank weapons that are classified as rockets to Ukraine, like the AT-4, and the longer-range Javelin, which is a guided missile.

That delineation worked well in the past with the MLRS and ATACMS weapons, but in more recent years the military has built weapons it calls “guided rockets” — like GMLRS — which are often older rocket designs upgraded to have guidance systems and movable fins on their nose to steer them.

The money part still holds true, though. GMLRS rockets remain far less expensive than the old ATACMS and the Precision Strike Missiles being developed to replace them.

How powerful are these rockets?

Using the HIMARS and GMLRS together can offer an amount of firepower that is similar to an airstrike — all from a mobile platform.

The upgrade in explosive power for the Ukrainian military will be profound. The warhead in each M31 GMLRS rocket contains a single charge of about 200 pounds of high explosives, while the 155-mm shells fired by howitzers contain only about 18 pounds.

Howitzers like the M777 can fire at a rate of about two to three rounds per minute. The GMLRS rockets can be fired singly or in a ripple of all six in just seconds, rivaling the power of an airstrike dropping guided bombs.

Does Russia have anything similar?

The Russian military has primarily used three types of unguided artillery rockets during the war in Ukraine.

The largest, the 300-mm Smerch, can fire a guided rocket, which makes it more accurate, and has a range similar to the GMLRS, though few have been seen in photos of the war. Most Smerch launches in Ukraine are unguided rockets, many containing cluster weapon warheads.

Do the American rockets have other advantages?

There’s one major advantage to the MLRS and HIMARS launchers: They can be fully reloaded within minutes.

Both vehicles have a winch that allows them to lower an empty pod to the ground, pick up a new, loaded pod, and pull it into place. The Russian launchers must be manually loaded, tube by tube.

Why hasn’t the U.S. sent longer-range ATACMS missiles to Ukraine?

President Biden said in an essay published Tuesday in The New York Times that the White House was “not encouraging or enabling Ukraine to strike beyond its borders.”

While reporting on the war, a senior defense official who served in field artillery and was not authorized to speak publicly about Pentagon war planning, told me that the Army has comparatively few ATACMS missiles remaining in its inventory, and those that it does have are earmarked for use in dire contingencies like a war with North Korea, or an effort to defend Taiwan from a Chinese invasion.

Sometimes, though, the U.S. Army launches an ATACMS missile to send a message, as it did just over a week ago during military exercises with South Korea, after North Korea had tested a suspected intercontinental ballistic missile.