Last week, close watchers of the many-sided war in Iraq and Syria learned from an apparently inadvertent Russian state television disclosure that Russia has upped the ante in its eight-week-old war in Syria, apparently adding ground-based artillery to the array of attack jets, strategic bombers, and helicopter gunships that have been pounding Islamic State terrorists and U.S.-backed rebels alike in the country.

Without fanfare, the U.S.-led coalition has escalated its involvement in the conflict in a similar way in recent weeks, adding artillery raids of its own to the steady thrum of air strikes against the Islamic State. In the U.S. case, the weapons involved are long-range, satellite-guided rockets, not howitzers, and the targets are in Iraq, not Syria.

Operation Inherent Resolve spokesman Col. Steve Warren first acknowledged the use of the M142 High Mobility Artillery Rocket System, or HIMARS—a staple of U.S. operations in Afghanistan—during a briefing last month. Since then, Inherent Resolve press releases have noted the use of rocket artillery on eight more days, most recently Sunday, when “rocket artillery” accounted for an unspecified number of 19 coalition strikes in Iraq.

Operated by the Army rather than the Air Force and presumably based at bases within Iraq rather than airfields elsewhere in the region like the jets flying in the air campaign, the deployment of HIMARS marks a little-noticed escalation in a U.S.-led war effort, although one, unlike missions by commandos, that poses little risk to U.S. personnel. Coalition spokespeople told the Washington Post that HIMARS has fired more than 400 rockets since midsummer, when the rocket strikes began.

According to the coalition spokespeople, the unit operating the rocket systems is deployed from Ft. Sill, Oklahoma, where the only HIMARS unit is the 1st Battalion, 14th Field Artillery.

Citing operational security, the coalition declined to specify which types of targets are being struck by rockets versus aircraft. But some clues as to how the weapon might be used against the Islamic State can be gleaned from the record of HIMARS and the two types of rockets it fires — the GMLRS and larger, longer-range ATACMS — in Afghanistan and during the last bout of U.S. involvement in Iraq.

At 196 pounds, the warhead of an M31 GMLRS-Unitary rocket is smaller than most munitions carried by manned aircraft, but heftier than the Hellfire missiles fired by Predator and Reaper drones. This quality, paired with its long range and its ability to fire even in inclement weather that might ground aircraft, made GMLRS (pronounced “Gimmlers” or sometimes “Glimmers”) the weapon of choice during messy urban “clearance” operations in the same cities where Iraqi troops face entrenched Islamic State forces today.

“GMLRS is highly effective in urban areas with a lower Collateral Damage Estimate and Risk Estimate Distance than most common air-delivered munitions,” a military after-action report on the 2006 battle of Ramadi raved.

During vicious battles in Baquba, Arab Jabour, and even downtown Baghdad, GMLRS proved their worth striking targeted buildings without damaging other structures nearby—a strength that proved especially useful when troops faced city blocks full of explosive-rigged houses, as Iraqi troops do today in Ramadi.

“There was a new rocket system called a glimmer that we had never heard of before being used,” Baquba veteran Alex Horton wrote in a blog post about the 2007 clearance of that city. “Dawn came, and with it, glimmer rockets and bunker busting bombs. There was intel on several explosive-rigged houses and IEDs before the operation started, and they were being destroyed en masse.”

In one famous incident, a GMLRS rocket struck a particular floor of a apartment building where insurgent snipers were holed up on Baghdad’s high-profile Haifa Street, just outside the Green Zone.

In rural Afghanistan, the newer incarnation of the rocket system, HIMARS, carved out a niche in special operations manhunting missions, complementing commando raids and accounting for an unknown proportion of the “kinetic strikes” that are usually chalked up to drones. In June 2007, according to a Guardian report based on leaked military documents, a special operations task force in Afghanistan used HIMARS in a failed effort to kill a senior Libyan al-Qaeda operative.

Soldiers who watched another HIMARS strike in Afghanistan on Thanksgiving Day 2009 via drone feed were amazed at the totality with which the big ATACMS rockets destroyed a compound where a regional insurgent leader was hiding, in the mountains where ground troops could not reach him and where he would have heard a helicopter assault coming.

They were even more amazed to see the targeted insurgent crawl out of the wreckage and walk away. “It was the best moment of the entire tour, until we saw that one person crawl out of there,” remembered an intelligence officer involved in that mission, who asked not to be named because of the nature of his job.

At the time, the fact that special operations forces were using HIMARS was a closely guarded secret, but the military has gradually acknowledged the system’s counterterrorism role. “While in Afghanistan, Battery A provided 24-hour HIMARS support to a joint special operations task force. The unit’s fire support operations provided coverage for nearly half of Afghanistan and supported more than 200 combat missions,” the Wisconsin National Guard announced when a HIMARS unit from that state returned home earlier this year.

A LinkedIn profile describes the role of an officer in another HIMARS battery in 2012: “While deployed to Afghanistan, planned and coordinated 2 ATACMS strikes in support of a Joint Special Operations Task Force, pursuing targets of national significance.”

With a campaign against Islamic State leaders apparently nested within the broader U.S.-led air war, HIMARS may be reprising that role today in Iraq.

Touted by one general in Afghanistan as “extraordinarily precise” and “accurate to a meter,” the weapon would seem well-suited to the Inherent Resolve campaign. The U.S. led-coalition has tried to avoid civilian casualties — to an unreasonable degree, some critics say—and has only acknowledged killing six civilians in Iraq and Syria so far, all due to air strikes.

Despite HIMARS’s vaunted precision, however, no weapon is perfect, a lesson that its record in Afghanistan also illustrates. During the 2010 battle of Marjah, two HIMARS-launched rockets missed their intended target, a compound from which U.S. Marines were taking fire, and instead struck a different compound.

The rockets killed at least 10 civilians, including children, and prompted theater command Gen. Stanley McChrystal to issue an apology and suspend HIMARS from use—briefly.

Wesley Morgan’s book on Afghanistan’s Pech valley is forthcoming from Random House. Follow him on Twitter: @wesleysmorgan.