WASHINGTON — U.S. and coalition forces carried out 187 airstrikes June 6-13, targeting ISIS fighters desperately attempting to fend off an assault by America's Kurdish allies, who launched an operation on June 6 to liberate the terror group's de facto capital.

The strikes represent a staggering display of U.S. airpower against a city of roughly 200,000 inhabitants, as the U.S. and its Kurdish allies, the Syrian Democratic Forces, ramp up operations to destroy the terror group in Syria. It also calls into question the level of U.S. firepower being brought to bear on the ISIS capital.

In comparison, from Oct. 17 to 24, during the first week of operations to liberate Mosul, the coalition carried out only 33 airstrikes. Mosul, a city of nearly 1.8 million people, is nine times larger than Raqqa.

However, officials in Baghdad argue that airstrike totals are not the best measure of coalition air support for its partner forces in Iraq and Syria. Strikes can consist of one or more separate engagements on multiple targets or target areas, they say, and actual targets hit by coalition aircraft during an airstrike represent a better picture of U.S. support. 

During the first week of operations to liberate Raqqa, coalition aircraft engaged roughly 347 targets, which includes fighting positions, enemy vehicles, boats and command centers. In Mosul, approximately 510 targets were engaged during the initial stages to liberate the populous city. 

The increase in operations tempo has not come without a cost. According to UN war crimes investigators, 300 civilians have been killed in Raqqa since March, mostly by U.S. and coalition airstrikes, as reported by Reuters.

"Coalition air strikes have intensified around the city," which has resulted in a "staggering loss of civilian life" said Paulo Pinheiro, chairman of the U.N. Commission of Inquiry.

The numbers highlight an intense air campaign by coalition forces in the much smaller and less dense city of Raqqa. To put it in perspective, "Mosul is about the size of Philadelphia — 200,000 buildings; 3,000 kilometers of road; 1.8 million people," said Maj. Gen. Joseph Martin, the land commander for forces in Operation Inherent Resolve.

"I'd have to probably go back to World War II to talk about a fight that has been this size and this magnitude with the requirements that the Iraqis have imposed upon themselves," he said.

Raqqa is a much smaller city. However, that doesn’t translate into an easy fight or quick victory for America’s Kurdish partners in Syria. ISIS fighters have had years to build up defenses, and the city’s liberation would represent the largest city captured by the Kurdish-led SDF forces, who number approximately 45,000 fighters, according to an estimate last December by Col. John Dorrian, a spokesperson for Operation Inherent Resolve.

Nearly 100,000 Iraqi, Peshmerga, and militia forces have taken part in the offensive to take Mosul, according to Reuters. Syrian Kurds are assaulting Raqqa with less than half that force and with far less capable weapon systems than their Iraqi counterparts, meaning U.S. and coalition advisers embedded with Kurdish forces on the ground will likely have to step up air support to bridge capability gaps of their Kurdish partners.

Heading into the Mosul offensive, Iraqi forces were equipped with their own organic air force, U.S. Abrams tanks, armored Humvees; and thousands of anti-tank rockets to include U.S. AT-4s, the M3 Carl Gustav recoilless rifle, and thousands of air-to-ground Hellfire missiles.

The small, but potent and highly capable Kurdish fighters leading the charge in Raqqa have been armed only with Guardian armored vehicles (up-armored Ford trucks), mortars, DShK heavy machine guns, and weapons that can "defeat vehicle-borne improvised explosive devices," a Pentagon official said.

Defense officials have been cautious in detailing whether Kurdish fighters will be equipped with anti-tank rockets out of concerns for Turkey, a NATO ally, which views the militants as terrorists. However, SDF forces are already well-equipped with RPG-7s, and a 2018 U.S. defense budget request lists thousands of AT-4s or SPG-9s — a Russian recoilless rifle — as future equipment for the Kurdish fighters.

Despite being scantily equipped and much smaller in numbers, Kurdish allies, bolstered by coalition air support, have made impressive and rapid gains in Raqqa. SDF forces have advanced to within a stone’s throw of the city center after reaching the walls of the Old City of Raqqa, according to officials at U.S. Central Command.

As U.S. and coalition forces have stepped up the fight in Raqqa, civilians have borne the toll of coalition airstrikes. However, officials in Baghdad contend their goal is always zero civilian casualties, but "the coalition will not abandon our commitment to our partners because of ISIS' inhuman tactics terrorizing civilians, using human shields, and fighting from protected sites such as schools, hospitals, religious sites and civilian neighborhoods," said an official at CENTCOM.